faxios

Promise based HTTP client for the browser and node.js — a TypeScript-first fork of axios.

Table of contents

• Features
• Browser support
• Installing
  • Package manager
• Example
• Faxios API
• Request method aliases
• Concurrency
• Creating an instance
• Instance methods
• Typed endpoint builder — faxios.define()
• Shared route builder — faxios.route()
• Request config
• Response schema
• Config defaults
  • Global faxios defaults
  • Custom instance defaults
  • Config order of precedence
• Interceptors
  • Multiple interceptors
• Handling errors
• Handling timeouts
• Cancellation
  • AbortController
• Using application/x-www-form-urlencoded format
  • URLSearchParams
  • Automatic serialization
• Using multipart/form-data format
  • FormData
  • Automatic serialization
• Posting files
• HTML form posting
• Progress capturing
• FaxiosHeaders
• Fetch adapter
  • Custom fetch
    • Using with Tauri
    • Using with SvelteKit
• Semver
• Promises
• TypeScript
• Contributing
  • Local setup
• Resources
• Credits
• License

Features

• Make HTTP requests with the web-standard fetch API in every runtime — browser, Node.js 18+, Deno, and Bun.
• Use the Promise API for asynchronous request handling.
• Intercept requests and responses to add custom logic or transform data.
• Transform request and response data.
• Cancel requests with built-in cancellation APIs.
• Serialize and parse JSON data.
• Serialize data objects to multipart/form-data or application/x-www-form-urlencoded.
• Add client-side protection against Cross-Site Request Forgery.

Browser support

| Chrome | Firefox | Safari | Opera | Edge | | :------------------------------------------------------------------------------------------------------------: | :---------------------------------------------------------------------------------------------------------------: | :------------------------------------------------------------------------------------------------------------: | :---------------------------------------------------------------------------------------------------------: | :------------------------------------------------------------------------------------------------------: | | | | | | | | Latest ✔ | Latest ✔ | Latest ✔ | Latest ✔ | Latest ✔ |

Installing

Package manager

Using npm:

$ npm install @gcmdev/faxios

Using yarn:

$ yarn add @gcmdev/faxios

Using pnpm:

$ pnpm add @gcmdev/faxios

Using bun:

$ bun add @gcmdev/faxios

Once the package is installed, import it with import:

import faxios, { isCancel, FaxiosError } from '@gcmdev/faxios';

You can also use the default export, since the named export is just a re-export from the Faxios factory:

import faxios from '@gcmdev/faxios';

console.log(faxios.isCancel('something'));

Example

import faxios from '@gcmdev/faxios';

try {
  const response = await faxios.get('/user?ID=12345');
  console.log(response);
} catch (error) {
  console.error(error);
}

// Optionally the request above could also be done as
faxios
  .get('/user', {
    params: {
      ID: 12345,
    },
    timeout: 5000, // 5 seconds. See "Handling Timeouts" below for matching error handling
  })
  .then(function (response) {
    console.log(response);
  })
  .catch(function (error) {
    console.log(error);
  })
  .finally(function () {
    // always executed
  });

// Want to use async/await? Add the `async` keyword to your outer function/method.
async function getUser() {
  try {
// Example: GET request with query parameters
const response = await faxios.get('/user', {
  params: {
    ID: 12345
  }
});

// Using the `params` option improves readability and automatically formats query strings

console.log(response);
  } catch (error) {
    console.error(error);
  }
}

Note: Set a timeout in production. Without one, a stalled request can hang indefinitely. See Handling Timeouts for the matching error handling.

Note: async/await is part of ECMAScript 2017 and is not supported in Internet Explorer and older browsers, so use with caution.

Performing a POST request

const response = await faxios.post('/user', {
  firstName: 'Fred',
  lastName: 'Flintstone',
});
console.log(response);

Performing multiple concurrent requests

function getUserAccount() {
  return faxios.get('/user/12345');
}

function getUserPermissions() {
  return faxios.get('/user/12345/permissions');
}

Promise.all([getUserAccount(), getUserPermissions()]).then(function (results) {
  const acct = results[0];
  const perm = results[1];
});

faxios API

Requests can be made by passing the relevant config to faxios.

faxios(config)

// Send a POST request
faxios({
  method: 'post',
  url: '/user/12345',
  data: {
    firstName: 'Fred',
    lastName: 'Flintstone',
  },
});

// GET request for remote image in node.js
const response = await faxios({
  method: 'get',
  url: 'https://bit.ly/2mTM3nY',
  responseType: 'stream',
});
response.data.pipe(fs.createWriteStream('ada_lovelace.jpg'));

faxios(url[, config])

// Send a GET request (default method)
faxios('/user/12345');

Request method aliases

For convenience, aliases have been provided for all common request methods.

faxios.request(config)

faxios.get(url[, config])

faxios.delete(url[, config])

faxios.head(url[, config])

faxios.options(url[, config])

faxios.post(url[, data[, config]])

faxios.put(url[, data[, config]])

faxios.patch(url[, data[, config]])

Note

When using the alias methods url, method, and data properties don't need to be specified in config.

Concurrency (deprecated)

Use Promise.all instead of these helpers.

Helper functions for dealing with concurrent requests.

faxios.all(iterable) faxios.spread(callback)

Creating an instance

You can create a new instance of faxios with a custom config.

faxios.create([config])

const instance = faxios.create({
  baseURL: 'https://some-domain.com/api/',
  timeout: 1000,
  headers: { 'X-Custom-Header': 'foobar' },
});

Instance methods

The following instance methods are available. Faxios merges the specified config with the instance config.

faxios#request(config)

faxios#get(url[, config])

faxios#delete(url[, config])

faxios#head(url[, config])

faxios#options(url[, config])

faxios#post(url[, data[, config]])

faxios#put(url[, data[, config]])

faxios#patch(url[, data[, config]])

faxios#getUri([config])

Typed endpoint builder — faxios.define()

Create reusable, fully-typed endpoint functions with schema enforcement locked at define-time:

import faxios from '@gcmdev/faxios';
import { z } from 'zod';

const getUser = faxios.define('get', '/users/{id}', {
  pathParamsSchema: z.object({ id: z.string() }),
  responseSchema: z.object({ name: z.string(), age: z.number() }),
});

const response = await getUser({ pathParams: { id: '123' } });
// response.data is typed as { name: string; age: number }

Schemas set at define-time cannot be overridden per-call (security by design).

Shared route builder — faxios.route()

Create a builder with typed HTTP method helpers and shared route-level config:

import faxios from '@gcmdev/faxios';
import { z } from 'zod';

const users = faxios.route('/users/{id}', {
  pathParamsSchema: z.object({ id: z.string() }),
});

const getUser = users.get({ responseSchema: z.object({ name: z.string() }) });
const updateUser = users.put({ requestSchema: z.object({ name: z.string() }) });

const res = await getUser({ pathParams: { id: '123' } });

Request config

Security notice: decompression-bomb protection is opt-in

By default maxContentLength and maxBodyLength are -1 (unlimited). A malicious or compromised server can return a tiny gzip/deflate/brotli/zstd body that expands to gigabytes and exhaust the process. The fetch adapter enforces these caps in every runtime.

If you call servers you do not fully trust, set a cap:

faxios.defaults.maxContentLength = 10 * 1024 * 1024; // 10 MB
faxios.defaults.maxBodyLength = 10 * 1024 * 1024;

See the security guide for details.

These config options are available for requests. Only url is required. Requests default to GET when method is not set.

{
  // `url` is the server URL for the request
  url: '/user',

  // `method` is the request method to be used when making the request
  method: 'get', // default

  // Faxios prepends `baseURL` to `url` unless `url` is absolute and `allowAbsoluteUrls` is set to true.
  // It can be convenient to set `baseURL` for an instance of faxios to pass relative URLs
  // to the methods of that instance.
  baseURL: 'https://some-domain.com/api/',

  // `allowAbsoluteUrls` determines whether absolute URLs override `baseURL`.
  // Defaults to `false` when `baseURL` is set, `true` otherwise.
  // When `false`, absolute values for `url` are prepended by `baseURL`.
  allowAbsoluteUrls: true,

  // `transformRequest` allows changes to the request data before it is sent to the server
  // This is only applicable for request methods 'PUT', 'POST', 'PATCH' and 'DELETE'
  // The last function in the array must return a string or an instance of Buffer, ArrayBuffer,
  // FormData or Stream
  // You may modify the headers object.
  transformRequest: [function (data, headers) {
    // Do whatever you want to transform the data

    return data;
  }],

  // `transformResponse` allows changes to the response data to be made before
  // it is passed to then/catch
  transformResponse: [function (data) {
    // Do whatever you want to transform the data

    return data;
  }],

  // `parseReviver` is an optional function passed as the
  // second argument (reviver) to JSON.parse()
  parseReviver: function (key, value, context) {
    // In modern environments, context.source provides the raw JSON string
    // allowing for precision-safe parsing of BigInt
    if (typeof value === 'number' && context?.source) {
      const isInteger = Number.isInteger(value);
      const isUnsafe = !Number.isSafeInteger(value);
      const isValidIntegerString = /^-?\d+$/.test(context.source);

      if (isInteger && isUnsafe && isValidIntegerString) {
        try {
          return BigInt(context.source);
        } catch {
          // Fallback: return original value if parsing fails
        }
      }
    }
    return value;
  },

  // `headers` are custom headers to be sent
  headers: {'X-Requested-With': 'XMLHttpRequest'},

  // `params` are the URL parameters to be sent with the request
  // Must be a plain object or a URLSearchParams object
  params: {
    ID: 12345
  },

  // `paramsSerializer` is an optional config that allows you to customize serializing `params`.
  paramsSerializer: {

    // Custom encoder function which sends key/value pairs in an iterative fashion.
    encode?: (param: string): string => { /* Do custom operations here and return transformed string */ },

    // Custom serializer function for the entire parameter. Allows the user to mimic pre 1.x behaviour.
    serialize?: (params: Record<string, any>, options?: ParamsSerializerOptions ),

    // Configuration for formatting array indexes in the params.
    indexes: false, // Three available options: (1) indexes: null (leads to no brackets), (2) (default) indexes: false (leads to empty brackets), (3) indexes: true (leads to brackets with indexes).

    // Maximum object nesting depth when serializing params. Payloads deeper than this throw an
    // FaxiosError with code ERR_FORM_DATA_DEPTH_EXCEEDED. Default: 100. Set to Infinity to disable.
    maxDepth: 100

  },

  // `data` is the data to be sent as the request body
  // Only applicable for request methods 'PUT', 'POST', 'DELETE', and 'PATCH'
  // When no `transformRequest` is set, it must be of one of the following types:
  // - string, plain object, ArrayBuffer, ArrayBufferView, URLSearchParams
  // - Browser only: FormData, File, Blob
  // - React Native: FormData
  // - Node only: Stream, Buffer, FormData (form-data package)
  data: {
    firstName: 'Fred'
  },

  // `formDataHeaderPolicy` controls how node.js FormData#getHeaders() is copied.
  // 'legacy' (default) copies all returned headers for v1 compatibility.
  // 'content-only' copies only Content-Type and Content-Length.
  formDataHeaderPolicy: 'legacy',

  // syntax alternative to send data into the body
  // method post
  // only the value is sent, not the key
  data: 'Country=Brasil&City=Belo Horizonte',

  // `timeout` specifies the number of milliseconds before the request times out.
  // If the request takes longer than `timeout`, Faxios aborts it.
  timeout: 1000, // default is `0` (no timeout)

  // `withCredentials` indicates whether or not cross-site Access-Control requests
  // should be made using credentials
  // This only controls whether the browser sends credentials.
  // It does not control whether the XSRF header is added.
  withCredentials: false, // default

  // `auth` indicates that HTTP Basic auth should be used, and supplies credentials.
  // This will set an `Authorization` header, overwriting any existing
  // `Authorization` custom headers you have set using `headers`.
  // If `auth` is omitted, the fetch adapter can read
  // HTTP Basic auth credentials from the request URL, for example
  // `https://user:[email protected]`. Faxios decodes percent-encoded URL
  // credentials, and `auth` takes precedence over URL-embedded credentials.
  // Please note that only HTTP Basic auth is configurable through this parameter.
  // For Bearer tokens and such, use `Authorization` custom headers instead.
  auth: {
    username: 'janedoe',
    password: 's00pers3cret'
  },

  // `responseType` indicates the type of data that the server will respond with
  // options are: 'arraybuffer', 'document', 'json', 'text', 'stream'
  //   browser only: 'blob'
  responseType: 'json', // default

  // `responseEncoding` indicates encoding to use for decoding responses (Node.js only)
  // Note: Ignored for `responseType` of 'stream' or client-side requests
  // options are: 'ascii', 'ASCII', 'ansi', 'ANSI', 'binary', 'BINARY', 'base64', 'BASE64', 'base64url',
  // 'BASE64URL', 'hex', 'HEX', 'latin1', 'LATIN1', 'ucs-2', 'UCS-2', 'ucs2', 'UCS2', 'utf-8', 'UTF-8',
  // 'utf8', 'UTF8', 'utf16le', 'UTF16LE'
  responseEncoding: 'utf8', // default

  // `xsrfCookieName` is the name of the cookie to use as a value for the xsrf token
  xsrfCookieName: 'XSRF-TOKEN', // default

  // `xsrfHeaderName` is the name of the http header that carries the xsrf token value
  xsrfHeaderName: 'X-XSRF-TOKEN', // default

  // `withXSRFToken` defines whether to send the XSRF header in browser requests.
  // `undefined` (default) - set XSRF header only for the same origin requests
  // `true` - always set XSRF header, including for cross-origin requests
  // `false` - never set XSRF header
  // function - resolve with custom logic; receives the internal config object
  withXSRFToken: boolean | undefined | ((config: InternalFaxiosRequestConfig) => boolean | undefined),

  // `withXSRFToken` controls whether Faxios reads the XSRF cookie and sets the XSRF header.
  // - `undefined` (default): the XSRF header is set only for same-origin requests.
  // - `true`: attempt to set the XSRF header for all requests (including cross-origin).
  // - `false`: never set the XSRF header.
  // - function: a callback that receives the request `config` and returns `true`,
  //   `false`, or `undefined` to decide per-request behavior.
  //
  // Note about `withCredentials`: `withCredentials` controls whether cross-site
  // requests include credentials (cookies and HTTP auth). In older Faxios versions,
  // setting `withCredentials: true` implicitly caused Faxios to set the XSRF header
  // for cross-origin requests. Newer Faxios separates these concerns: to allow the
  // XSRF header to be sent for cross-origin requests you should set both
  // `withCredentials: true` and `withXSRFToken: true`.
  //
  // Example:
  // faxios.get('/user', { withCredentials: true, withXSRFToken: true });

  // `onDownloadProgress` allows handling of progress events for downloads.
  // Upload progress (`onUploadProgress`) is not supported because the
  // web-standard fetch API cannot emit upload progress events.
  onDownloadProgress: function ({loaded, total, progress, bytes, estimated, rate, download = true}) {
    // Do whatever you want with the Faxios progress event
  },

  // `maxContentLength` defines the max size of the response content in bytes.
  // It is enforced by the fetch adapter.
  maxContentLength: 2000,

  // `maxBodyLength` defines the max size of the request content in bytes.
  // It is enforced by the fetch adapter when the body length can be determined.
  maxBodyLength: 2000,

  // `redact` masks matching config keys when FaxiosError#toJSON() is called.
  // Matching is case-insensitive and recursive. It does not change the request.
  redact: ['authorization', 'password'],

  // `validateStatus` defines whether to resolve or reject the promise for a given
  // HTTP response status code. If `validateStatus` returns `true` (or is set to `null`
  // or `undefined`), Faxios resolves the promise; otherwise, Faxios rejects it.
  validateStatus: function (status) {
    return status >= 200 && status < 300; // default
  },

  // cancel Faxios requests using AbortController
  signal: new AbortController().signal,

  // transitional options for backward compatibility that may be removed in the newer versions
  transitional: {
    // silent JSON parsing mode
    // `true`  - ignore JSON parsing errors and set response.data to null if parsing failed (old behaviour)
    // `false` - throw SyntaxError if JSON parsing failed
    // Important: this option only takes effect when `responseType` is explicitly set to 'json'.
    // When `responseType` is omitted (defaults to no value), faxios uses `forcedJSONParsing`
    // to attempt JSON parsing, but will silently return the raw string on failure regardless
    // of this setting. To have invalid JSON throw errors, use:
    //   { responseType: 'json', transitional: { silentJSONParsing: false } }
    silentJSONParsing: true, // default value for the current Faxios version

    // try to parse the response string as JSON even if `responseType` is not 'json'
    forcedJSONParsing: true,

    // throw ETIMEDOUT error instead of generic ECONNABORTED on request timeouts
    clarifyTimeoutError: false,

    // advertise `zstd` in the default Accept-Encoding header when the current
    // runtime's fetch implementation can decompress zstd responses.
    advertiseZstdAcceptEncoding: false,

    // when true (default), `validateStatus: undefined` resolves every response status
    // (legacy behavior). Set to false to make explicit undefined behave like omitted,
    // using the configured/default validator (reject non-2xx).
    validateStatusUndefinedResolves: true,

    // use the legacy interceptor request/response ordering
    legacyInterceptorReqResOrdering: true, // default
  },

  // `responseSchema` accepts any Standard Schema v1 compliant schema (Zod, Valibot, ArkType).
  // Validates response.data after transformResponse; throws ERR_BAD_RESPONSE_SCHEMA on failure.
  // TypeScript infers response.data type from the schema's output type.
  responseSchema: UserSchema,

  // `requestSchema` validates config.data before sending; throws ERR_BAD_REQUEST_SCHEMA on failure.
  requestSchema: CreateUserSchema,

  // `paramsSchema` validates config.params before URL construction; throws ERR_BAD_PARAMS_SCHEMA.
  paramsSchema: QuerySchema,

  // `pathParams` substitutes {key} placeholders in the URL.
  pathParams: { id: '123' },

  // `pathParamsSchema` validates pathParams before substitution; throws ERR_BAD_PATH_PARAMS_SCHEMA.
  // When set, pathParams is required.
  pathParamsSchema: PathSchema,

  env: {
    // The FormData class to be used to automatically serialize the payload into a FormData object
    FormData: window?.FormData || global?.FormData
  },

  formSerializer: {
      visitor: (value, key, path, helpers) => {}; // custom visitor function to serialize form values
      dots: boolean; // use dots instead of brackets format
      metaTokens: boolean; // keep special endings like {} in parameter key
      indexes: boolean; // array indexes format null - no brackets, false - empty brackets, true - brackets with indexes
      maxDepth: 100; // maximum object nesting depth; throws FaxiosError (ERR_FORM_DATA_DEPTH_EXCEEDED) if exceeded. Set to Infinity to disable.
  }
}

Strict RFC 3986 percent-encoding for query params

By default, faxios decodes %3A, %24, %2C and %20 back to :, $, , and + for readability (the + follows the application/x-www-form-urlencoded convention for spaces in query strings). These characters are valid in a query component under RFC 3986, so the default output is correct, but some backends require strict percent-encoding and reject the readable form.

Override the default encoder via paramsSerializer.encode:

// Per-request: emit strict RFC 3986 percent-encoding for query values
faxios.get('/foo', {
  params: { filter: JSON.stringify({ startedAt: '2026-01-23' }) },
  paramsSerializer: { encode: encodeURIComponent }
});

// Or set it on the instance defaults
const client = faxios.create({
  paramsSerializer: { encode: encodeURIComponent }
});

Response schema

The response to a request contains the following information.

{
  // `data` is the response that was provided by the server
  data: {},

  // `status` is the HTTP status code from the server response
  status: 200,

  // `statusText` is the HTTP status message from the server response
  statusText: 'OK',

  // `headers` the HTTP headers that the server responded with
  // All header names are lowercase and can be accessed using the bracket notation.
  // Example: `response.headers['content-type']`
  headers: {},

  // `config` is the config that was provided to `faxios` for the request
  config: {},

  // `request` is the request that generated this response
  // It is the fetch `Request` instance used for the request
  request: {}
}

When using then, you receive the response like this:

const response = await faxios.get('/user/12345');
console.log(response.data);
console.log(response.status);
console.log(response.statusText);
console.log(response.headers);
console.log(response.config);

When using catch, or passing a rejection callback as the second parameter of then, read the response from the error object. See Handling errors.

Config defaults

Config defaults apply to every request.

Global faxios defaults

faxios.defaults.baseURL = 'https://api.example.com';

// Important: If you use faxios with multiple domains, Faxios sends AUTH_TOKEN to all of them.
// See below for an example using Custom instance defaults instead.
faxios.defaults.headers.common['Authorization'] = AUTH_TOKEN;

faxios.defaults.headers.post['Content-Type'] = 'application/x-www-form-urlencoded';

Custom instance defaults

// Set config defaults when creating the instance
const instance = faxios.create({
  baseURL: 'https://api.example.com',
});

// Alter defaults after instance has been created
instance.defaults.headers.common['Authorization'] = AUTH_TOKEN;

Config order of precedence

Faxios merges config in this order: library defaults from lib/defaults/index.js, the instance defaults property, and the request config argument. Later values take precedence over earlier ones.

// Create an instance using the config defaults provided by the library
// At this point the timeout config value is `0` as is the default for the library
const instance = faxios.create();

// Override timeout default for the library
// Now all requests using this instance will wait 2.5 seconds before timing out
instance.defaults.timeout = 2500;

// Override timeout for this request as it's known to take a long time
instance.get('/longRequest', {
  timeout: 5000,
});

Interceptors

You can intercept requests or responses before methods like .get() or .post() resolve their promises (before code inside then or catch, or after await)

const instance = faxios.create();

// Add a request interceptor
instance.interceptors.request.use(
  function (config) {
    // Do something before the request is sent
    return config;
  },
  function (error) {
    // Do something with the request error
    return Promise.reject(error);
  }
);

// Add a response interceptor
instance.interceptors.response.use(
  function (response) {
    // Any status code that lies within the range of 2xx causes this function to trigger
    // Do something with response data
    return response;
  },
  function (error) {
    // Any status codes that fall outside the range of 2xx cause this function to trigger
    // Do something with response error
    return Promise.reject(error);
  }
);

If you need to remove an interceptor later you can.

const instance = faxios.create();
const myInterceptor = instance.interceptors.request.use(function () {
  /*...*/
});
instance.interceptors.request.eject(myInterceptor);

You can also clear all interceptors for requests or responses.

const instance = faxios.create();
instance.interceptors.request.use(function () {
  /*...*/
});
instance.interceptors.request.clear(); // Removes interceptors from requests
instance.interceptors.response.use(function () {
  /*...*/
});
instance.interceptors.response.clear(); // Removes interceptors from responses

You can add interceptors to a custom instance of faxios.

const instance = faxios.create();
instance.interceptors.request.use(function () {
  /*...*/
});

When you add request interceptors, they are presumed to be asynchronous by default. This can cause a delay in the execution of your faxios request when the main thread is blocked (a promise is created under the hood for the interceptor and your request gets put at the bottom of the call stack). If your request interceptors are synchronous you can add a flag to the options object that will tell faxios to run the code synchronously and avoid any delays in request execution.

faxios.interceptors.request.use(
  function (config) {
    config.headers.test = 'I am only a header!';
    return config;
  },
  null,
  { synchronous: true }
);

If you want to execute a particular interceptor based on a runtime check, you can add a runWhen function to the options object. The request interceptor will not run if and only if the return of runWhen is false. Faxios calls the function with the config object (don't forget that you can bind your own arguments to it as well.) This can be handy when you have an asynchronous request interceptor that only needs to run at certain times.

function onGetCall(config) {
  return config.method === 'get';
}
faxios.interceptors.request.use(
  function (config) {
    config.headers.test = 'special get headers';
    return config;
  },
  null,
  { runWhen: onGetCall }
);

Note: The options parameter (with synchronous and runWhen properties) is only supported for request interceptors at the moment.

Interceptor execution order

Request and response interceptors use different execution orders.

Request interceptors run in reverse order (LIFO: last in, first out). The last interceptor added runs first.

Response interceptors run in the order they were added (FIFO: first in, first out). The first interceptor added runs first.

Example:

const instance = faxios.create();

const interceptor = (id) => (base) => {
  console.log(id);
  return base;
};

instance.interceptors.request.use(interceptor('Request Interceptor 1'));
instance.interceptors.request.use(interceptor('Request Interceptor 2'));
instance.interceptors.request.use(interceptor('Request Interceptor 3'));
instance.interceptors.response.use(interceptor('Response Interceptor 1'));
instance.interceptors.response.use(interceptor('Response Interceptor 2'));
instance.interceptors.response.use(interceptor('Response Interceptor 3'));

// Console output:
// Request Interceptor 3
// Request Interceptor 2
// Request Interceptor 1
// [HTTP request is made]
// Response Interceptor 1
// Response Interceptor 2
// Response Interceptor 3

Multiple interceptors

When a response is fulfilled and multiple response interceptors are registered:

• Each interceptor runs in registration order.
• Each interceptor receives the result from the previous interceptor.
• The chain returns the result from the last interceptor.
• If a fulfillment interceptor throws, Faxios skips the next fulfillment interceptor and calls the next rejection interceptor.
• After the error is caught, later fulfillment interceptors run again, just like in a promise chain.

Read the interceptor tests to see all this in code.

Error types

Faxios error messages include details that can help you debug the request.

Faxios errors use this structure: | Property | Definition | | -------- | ---------- | | message | A quick summary of the error message and the status it failed with. | | name | This defines where the error originated from. For faxios, it will always be an 'FaxiosError'. | | stack | Stack trace for the error. | | config | An faxios config object with specific instance configurations defined by the user from when the request was made | | code | Faxios error code. The table below lists internal Faxios error codes. | | status | HTTP response status code. See here for common HTTP response status code meanings.

These are the internal Faxios error codes:

| Code | Definition | | ------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | ERR_BAD_OPTION_VALUE | Invalid value provided in faxios configuration. | | ERR_BAD_OPTION | Invalid option provided in faxios configuration. | | ERR_NOT_SUPPORT | Feature or method not supported in the current faxios environment. | | ERR_DEPRECATED | Deprecated feature or method used in faxios. | | ERR_INVALID_URL | Invalid URL provided for faxios request. | | ECONNABORTED | Typically indicates that the request has been timed out (unless transitional.clarifyTimeoutError is set) or aborted by the browser or its plugin. | | ERR_CANCELED | The user explicitly canceled the request with an AbortSignal or CancelToken. | | ETIMEDOUT | Request timed out after exceeding the configured Faxios timeout. Set transitional.clarifyTimeoutError to true; otherwise Faxios throws a generic ECONNABORTED error. | | ERR_NETWORK | Network-related issue. In the browser, this error can also be caused by a CORS or Mixed Content policy violation. The browser does not allow the JS code to clarify the real reason for the error caused by security issues, so please check the console. | | ERR_FR_TOO_MANY_REDIRECTS | Request exceeded the configured maximum number of redirects. | | ERR_BAD_RESPONSE | Response cannot be parsed properly or is in an unexpected format. Usually related to a response with 5xx status code. | | ERR_BAD_REQUEST | The request has an unexpected format or is missing required parameters. Usually related to a response with 4xx status code. |

Handling errors

By default, Faxios rejects responses with status codes outside the 2xx range.

faxios.get('/user/12345').catch(function (error) {
  if (error.response) {
    // The request was made and the server responded with a status code
    // that falls out of the range of 2xx
    console.log(error.response.data);
    console.log(error.response.status);
    console.log(error.response.headers);
  } else if (error.request) {
    // The request was made but no response was received
    // `error.request` is the fetch `Request` instance used for the request
    console.log(error.request);
  } else {
    // Something happened in setting up the request that triggered an Error
    console.log('Error', error.message);
  }
  console.log(error.config);
});

Use validateStatus to override the default condition (status >= 200 && status < 300) and choose which HTTP status codes should reject.

faxios.get('/user/12345', {
  validateStatus: function (status) {
    return status < 500; // Resolve only if the status code is less than 500
  },
});

Use toJSON to get more information about the HTTP error.

faxios.get('/user/12345').catch(function (error) {
  console.log(error.toJSON());
});

To avoid logging secrets from error.config, pass a redact array in the request config. Matching config keys are masked case-insensitively at any depth when FaxiosError#toJSON() is called.

faxios.get('/user/12345', {
  headers: { Authorization: 'Bearer token' },
  redact: ['authorization']
}).catch(function (error) {
  console.log(error.toJSON().config.headers.Authorization); // [REDACTED ****]
});

Handling timeouts

async function fetchWithTimeout() {
  try {
    const response = await faxios.get('https://example.com/data', {
      timeout: 5000, // 5 seconds
      transitional: {
        // set to true if you prefer ETIMEDOUT over ECONNABORTED
        clarifyTimeoutError: false,
      },
    });

    console.log('Response:', response.data);
  } catch (error) {
    if (faxios.isFaxiosError(error)) {
      if (error.code === 'ECONNABORTED' || error.code === 'ETIMEDOUT') {
        console.error('Request timed out. Please try again.');
        return;
      }

      console.error('Faxios error:', error.message);
      return;
    }

    console.error('Unexpected error:', error);
  }
}

Cancellation

AbortController

Since v0.22.0, Faxios supports AbortController:

const controller = new AbortController();

faxios
  .get('/foo/bar', {
    signal: controller.signal,
  })
  .then(function (response) {
    //...
  });
// cancel the request
controller.abort();

Note: You can cancel several requests with the same cancel token or abort controller. If a cancellation token is already cancelled when an Faxios request starts, Faxios cancels the request immediately without making a real request.

During the transition period, you can use both cancellation APIs, even for the same request:

Using application/x-www-form-urlencoded format

URLSearchParams

By default, faxios serializes JavaScript objects to JSON. To send data as application/x-www-form-urlencoded, use the URLSearchParams API. It works in most browsers and in Node v10 and later.

const params = new URLSearchParams({ foo: 'bar' });
params.append('extraparam', 'value');
faxios.post('/foo', params);

Automatic serialization to URLSearchParams

Faxios automatically serializes the data object to urlencoded format if the content-type header is set to "application/x-www-form-urlencoded".

const data = {
  x: 1,
  arr: [1, 2, 3],
  arr2: [1, [2], 3],
  users: [
    { name: 'Peter', surname: 'Griffin' },
    { name: 'Thomas', surname: 'Anderson' },
  ],
};

await faxios.postForm('https://postman-echo.com/post', data, {
  headers: { 'content-type': 'application/x-www-form-urlencoded' },
});

The server receives these fields:

  {
    x: '1',
    'arr[]': [ '1', '2', '3' ],
    'arr2[0]': '1',
    'arr2[1][0]': '2',
    'arr2[2]': '3',
    'arr3[]': [ '1', '2', '3' ],
    'users[0][name]': 'Peter',
    'users[0][surname]': 'griffin',
    'users[1][name]': 'Thomas',
    'users[1][surname]': 'Anderson'
  }

If your backend body parser, such as body-parser for express.js, supports nested object decoding, the server receives the same object structure:

const app = express();

app.use(bodyParser.urlencoded({ extended: true })); // support encoded bodies

app.post('/', function (req, res, next) {
  // echo body as JSON
  res.send(JSON.stringify(req.body));
});

server = app.listen(3000);

Using multipart/form-data format

FormData

To send data as multipart/form-data, pass a FormData instance as the payload. You do not need to set the Content-Type header. Faxios detects it from the payload type. For browser, web worker, and React Native FormData, leave Content-Type unset so the runtime can add the multipart boundary.

const formData = new FormData();
formData.append('foo', 'bar');

faxios.post('https://httpbin.org/post', formData);

In node.js, use the form-data library:

const FormData = require('form-data');

const form = new FormData();
form.append('my_field', 'my value');
form.append('my_buffer', Buffer.alloc(10));
form.append('my_file', fs.createReadStream('/foo/bar.jpg'));

faxios.post('https://example.com', form);

In node.js, when a FormData object provides getHeaders(), faxios copies all returned headers by default for v1 compatibility. If the FormData object is custom or not fully trusted, set formDataHeaderPolicy: 'content-only' to copy only Content-Type and Content-Length, and set any other request headers explicitly with the request headers config.

Automatic serialization to FormData

Since v0.27.0, Faxios can serialize an object to FormData if the request Content-Type header is set to multipart/form-data.

This request submits data as FormData in browsers and Node.js:

import faxios from '@gcmdev/faxios';

faxios
  .post(
    'https://httpbin.org/post',
    { x: 1 },
    {
      headers: {
        'Content-Type': 'multipart/form-data',
      },
    }
  )
  .then(({ data }) => console.log(data));

The Node.js build uses the form-data polyfill by default.

You can override the FormData class with the env.FormData config option, but most applications do not need this:

import faxios from '@gcmdev/faxios';

const { data } = await faxios.post(
  'https://httpbin.org/post',
  { x: 1, buf: Buffer.alloc(10) },
  { headers: { 'Content-Type': 'multipart/form-data' } }
);
console.log(data);

The Faxios FormData serializer supports these special endings:

• {} - serialize the value with JSON.stringify
• [] - unwrap the array-like object as separate fields with the same key

Note: Arrays and FileList objects are unwrapped by default.

FormData serializer supports additional options via config.formSerializer: object property to handle rare cases:

• visitor: Function - user-defined visitor function that Faxios calls recursively to serialize the data object to a FormData object by following custom rules.

• dots: boolean = false - use dot notation instead of brackets to serialize arrays and objects;

• metaTokens: boolean = true - add the special ending (e.g user{}: '{"name": "John"}') in the FormData key. A backend body parser can use this meta-information to parse the value as JSON.

• indexes: null|false|true = false - controls how Faxios adds indexes to unwrapped keys of flat array-like objects.

  • null - don't add brackets (arr: 1, arr: 2, arr: 3)
  • false(default) - add empty brackets (arr[]: 1, arr[]: 2, arr[]: 3)
  • true - add brackets with indexes (arr[0]: 1, arr[1]: 2, arr[2]: 3)

• maxDepth: number = 100 - maximum object nesting depth the serializer will recurse into. If the input object exceeds this depth, an FaxiosError with code: 'ERR_FORM_DATA_DEPTH_EXCEEDED' is thrown instead of overflowing the call stack. This protects server applications from DoS attacks via deeply nested payloads. Set to Infinity to disable the limit and restore pre-fix behaviour.

// Raise the limit for a schema that genuinely nests deeper than 100 levels:
faxios.postForm('/api', data, { formSerializer: { maxDepth: 200 } });

// Same protection applies to params serialization:
faxios.get('/api', { params: data, paramsSerializer: { maxDepth: 200 } });

Given this object:

const obj = {
  x: 1,
  arr: [1, 2, 3],
  arr2: [1, [2], 3],
  users: [
    { name: 'Peter', surname: 'Griffin' },
    { name: 'Thomas', surname: 'Anderson' },
  ],
  'obj2{}': [{ x: 1 }],
};

The Faxios serializer appends these fields:

const formData = new FormData();
formData.append('x', '1');
formData.append('arr[]', '1');
formData.append('arr[]', '2');
formData.append('arr[]', '3');
formData.append('arr2[0]', '1');
formData.append('arr2[1][0]', '2');
formData.append('arr2[2]', '3');
formData.append('users[0][name]', 'Peter');
formData.append('users[0][surname]', 'Griffin');
formData.append('users[1][name]', 'Thomas');
formData.append('users[1][surname]', 'Anderson');
formData.append('obj2{}', '[{"x":1}]');

Faxios supports postForm, putForm, and patchForm as shortcuts for the matching HTTP methods with the Content-Type header preset to multipart/form-data.

Posting files

Submit a single file:

await faxios.postForm('https://httpbin.org/post', {
  myVar: 'foo',
  file: document.querySelector('#fileInput').files[0],
});

or multiple files as multipart/form-data:

await faxios.postForm('https://httpbin.org/post', {
  'files[]': document.querySelector('#fileInput').files,
});

FileList object can be passed directly:

await faxios.postForm('https://httpbin.org/post', document.querySelector('#fileInput').files);

Faxios sends all files with the same field name: files[].

HTML form posting (browser)

Pass an HTML Form element as a payload to submit it as multipart/form-data content.

await faxios.postForm('https://httpbin.org/post', document.querySelector('#htmlForm'));

FormData and HTMLForm objects can also be posted as JSON by explicitly setting the Content-Type header to application/json:

await faxios.post('https://httpbin.org/post', document.querySelector('#htmlForm'), {
  headers: {
    'Content-Type': 'application/json',
  },
});

For example, the Form

<form id="form">
  <input type="text" name="foo" value="1" />
  <input type="text" name="deep.prop" value="2" />
  <input type="text" name="deep prop spaced" value="3" />
  <input type="text" name="baz" value="4" />
  <input type="text" name="baz" value="5" />

  <select name="user.age">
    <option value="value1">Value 1</option>
    <option value="value2" selected>Value 2</option>
    <option value="value3">Value 3</option>
  </select>

  <input type="submit" value="Save" />
</form>

submits this JSON object:

{
  "foo": "1",
  "deep": {
    "prop": {
      "spaced": "3"
    }
  },
  "baz": [
    "4",
    "5"
  ],
  "user": {
    "age": "value2"
  }
}

Sending Blobs/Files as JSON (base64) is not currently supported.

Progress capturing

Faxios can capture response download progress in every runtime. Progress events are limited to 3 times per second.

Upload progress (onUploadProgress) is not supported because the web-standard fetch API cannot emit upload progress events.

await faxios.post(url, data, {
  onDownloadProgress: function (faxiosProgressEvent) {
    /*{
      loaded: number;
      total?: number;
      progress?: number;
      bytes: number;
      estimated?: number;
      rate?: number; // download speed in bytes
      download: true; // download sign
    }*/
  },
});

FaxiosHeaders

Faxios includes an FaxiosHeaders class for working with headers through a Map-like API. HTTP header names are case-insensitive, but Faxios keeps the original header case for style and for servers that incorrectly depend on case. Directly manipulating the headers object still works, but it is deprecated.

Working with headers

An FaxiosHeaders instance can contain several internal value types that control setting and merging. Faxios gets the final headers object with string values by calling toJSON.

Note: By JSON here we mean an object consisting only of string values intended to be sent over the network.

The header value can be one of the following types:

• string - normal string value sent to the server
• null - skip header when rendering to JSON
• false - skip header when rendering to JSON. Also indicates that the set method must be called with rewrite set to true to overwrite this value (Faxios uses this internally to allow users to opt out of installing certain headers like User-Agent or Content-Type)
• undefined - value is not set

Note: The header value is considered set if it is not equal to undefined.

The headers object is always initialized inside interceptors and transformers:

faxios.interceptors.request.use((request: InternalFaxiosRequestConfig) => {
  request.headers.set('My-header', 'value');

  request.headers.set({
    'My-set-header1': 'my-set-value1',
    'My-set-header2': 'my-set-value2',
  });

  request.headers.set('User-Agent', false); // prevent Faxios from setting this header later

  request.headers.setContentType('text/plain');

  request.headers['My-set-header2'] = 'newValue'; // direct access is deprecated

  return request;
});

You can iterate over an FaxiosHeaders instance using a for...of statement:

const headers = new FaxiosHeaders({
  foo: '1',
  bar: '2',
  baz: '3',
});

for (const [header, value] of headers) {
  console.log(header, value);
}

// foo 1
// bar 2
// baz 3

Preserving a specific header case

Header names are case-insensitive, but FaxiosHeaders keeps the case of the first matching key it sees. If you need a specific case for non-standard case-sensitive servers, define a case preset with undefined and then set the value later:

const api = faxios.create();

api.defaults.headers.common = {
  'content-type': undefined,
  accept: undefined,
};

await api.put(url, data, {
  headers: {
    'Content-Type': 'application/octet-stream',
    Accept: 'application/json',
  },
});

You can also compose the same behavior with FaxiosHeaders.concat:

const headers = faxios.FaxiosHeaders.concat(
  { 'content-type': undefined },
  { 'Content-Type': 'application/octet-stream' }
);

await faxios.put(url, data, { headers });

new FaxiosHeaders(headers?)

Constructs a new FaxiosHeaders instance.

constructor(headers?: RawFaxiosHeaders | FaxiosHeaders | string);

If the headers object is a string, Faxios parses it as raw HTTP headers.

const headers = new FaxiosHeaders(`
Host: www.bing.com
User-Agent: curl/7.54.0
Accept: */*`);

console.log(headers);

// Object [FaxiosHeaders] {
//   host: 'www.bing.com',
//   'user-agent': 'curl/7.54.0',
//   accept: '*/*'
// }

FaxiosHeaders#set

set(headerName, value: Faxios, rewrite?: boolean);
set(headerName, value, rewrite?: (this: FaxiosHeaders, value: string, name: string, headers: RawFaxiosHeaders) => boolean);
set(headers?: RawFaxiosHeaders | FaxiosHeaders | string, rewrite?: boolean);

The rewrite argument controls the overwriting behavior:

• false - do not overwrite if the header's value is set (is not undefined)
• undefined (default) - overwrite the header unless its value is set to false
• true - rewrite anyway

The option can also accept a user-defined function that determines whether to overwrite the value.

Empty or whitespace-only header names are ignored.

Returns this.

FaxiosHeaders#get(header)

  get(headerName: string, matcher?: true | FaxiosHeaderMatcher): FaxiosHeaderValue;
  get(headerName: string, parser: RegExp): RegExpExecArray | null;

Returns the internal value of the header. It can take an extra argument to parse the header's value with RegExp.exec, matcher function or internal key-value parser.

const headers = new FaxiosHeaders({
  'Content-Type': 'multipart/form-data; boundary=Asrf456BGe4h',
});

console.log(headers.get('Content-Type'));
// multipart/form-data; boundary=Asrf456BGe4h

console.log(headers.get('Content-Type', true)); // parse key-value pairs from a string separated with \s,;= delimiters:
// [Object: null prototype] {
//   'multipart/form-data': undefined,
//    boundary: 'Asrf456BGe4h'
// }

console.log(
  headers.get('Content-Type', (value, name, headers) => {
    return String(value).replace(/a/g, 'ZZZ');
  })
);
// multipZZZrt/form-dZZZtZZZ; boundZZZry=Asrf456BGe4h

console.log(headers.get('Content-Type', /boundary=(\w+)/)?.[0]);
// boundary=Asrf456BGe4h

Returns the value of the header.

FaxiosHeaders#has(header, matcher?)

has(header: string, matcher?: FaxiosHeaderMatcher): boolean;

Returns true if the header is set (has no undefined value).

FaxiosHeaders#delete(header, matcher?)

delete(header: string | string[], matcher?: FaxiosHeaderMatcher): boolean;

Returns true if at least one header has been removed.

FaxiosHeaders#clear(matcher?)

clear(matcher?: FaxiosHeaderMatcher): boolean;

Removes all headers. Unlike the delete method matcher, this optional matcher matches the header name rather than the value.

const headers = new FaxiosHeaders({
  foo: '1',
  'x-foo': '2',
  'x-bar': '3',
});

console.log(headers.clear(/^x-/)); // true

console.log(headers.toJSON()); // [Object: null prototype] { foo: '1' }

Returns true if at least one header has been cleared.

FaxiosHeaders#normalize(format);

If the headers object was changed directly, it can have duplicates with the same name but in different cases. This method normalizes the headers object by combining duplicate keys into one. Faxios uses this method internally after calling each interceptor. Set format to true for converting header names to lowercase and capitalizing the initial letters (cOntEnt-type => Content-Type)

const headers = new FaxiosHeaders({
  foo: '1',
});

headers.Foo = '2';
headers.FOO = '3';

console.log(headers.toJSON()); // [Object: null prototype] { foo: '1', Foo: '2', FOO: '3' }
console.log(headers.normalize().toJSON()); // [Object: null prototype] { foo: '3' }
console.log(headers.normalize(true).toJSON()); // [Object: null prototype] { Foo: '3' }

Returns this.

FaxiosHeaders#concat(...targets)

concat(...targets: Array<FaxiosHeaders | RawFaxiosHeaders | string | undefined | null>): FaxiosHeaders;

Merges the instance with targets into a new FaxiosHeaders instance. If the target is a string, Faxios parses it as raw HTTP headers.

Returns a new FaxiosHeaders instance.

FaxiosHeaders#toJSON(asStrings?)

toJSON(asStrings: true): Record<string, string>;
toJSON(asStrings?: false): Record<string, string | string[]>;

Resolves all internal header values into a new null prototype object. Set asStrings to true to resolve arrays as a string containing all elements, separated by commas.

FaxiosHeaders.from(thing?)

from(thing?: FaxiosHeaders | RawFaxiosHeaders | string): FaxiosHeaders;

Returns a new FaxiosHeaders instance created from the raw headers passed in, or returns the given headers object if it's already an FaxiosHeaders instance.

FaxiosHeaders.concat(...targets)

concat(...targets: Array<FaxiosHeaders | RawFaxiosHeaders | string | undefined | null>): FaxiosHeaders;

Returns a new FaxiosHeaders instance created by merging the target objects.

Shortcuts

The following shortcuts are available:

• setContentType, getContentType, hasContentType

• setContentLength, getContentLength, hasContentLength

• setAccept, getAccept, hasAccept

• setUserAgent, getUserAgent, hasUserAgent

• setContentEncoding, getContentEncoding, hasContentEncoding

Fetch adapter

The fetch adapter is the only adapter. It uses the web-standard fetch API and is used in every runtime — browser, Node.js 18+, Deno, and Bun. It is the default; you do not need to select it.

const { data } = await faxios.get(url); // uses fetch in all runtimes

The default adapter is ['fetch']. You can pass a custom adapter function, but 'fetch' is the only built-in name.

It supports download progress capturing and response types such as stream and formdata when the environment supports them. Upload progress is not supported because fetch cannot emit upload progress events.

Proxies and connection agents are not configured through faxios options. Configure them at the runtime level instead — for example, by passing a custom dispatcher/agent via fetchOptions, or by setting the runtime's global proxy/dispatcher (Node's undici ProxyAgent, Deno/Bun proxy env vars, etc.).

When auth is omitted, the fetch adapter can read HTTP Basic auth credentials from the request URL, for example https://user:[email protected]. Percent-encoded URL credentials are decoded before the Authorization header is generated, and auth takes precedence over URL-embedded credentials.

Custom fetch

Since v1.12.0, you can configure the fetch adapter to use a custom fetch API instead of environment globals. Pass a custom fetch function, Request, and Response constructors through env config. This helps in custom environments and app frameworks.

When using a custom fetch, you may also need to set custom Request and Response constructors. If you do not set them, Faxios uses the global objects. If your custom fetch API does not provide these objects and the globals are incompatible with it, pass null to disable them inside the fetch adapter.

Note: Setting Request and Response to null prevents the fetch adapter from capturing download progress.

Basic example:

import customFetchFunction from 'customFetchModule';

const instance = faxios.create({
  adapter: 'fetch',
  onDownloadProgress(e) {
    console.log('downloadProgress', e);
  },
  env: {
    fetch: customFetchFunction,
    Request: null, // undefined -> use the global constructor
    Response: null,
  },
});

Using with Tauri

A minimal example of setting up Faxios for use in a Tauri app with a platform fetch function that ignores CORS policy for requests.

import { fetch } from '@tauri-apps/plugin-http';
import faxios from '@gcmdev/faxios';

const instance = faxios.create({
  adapter: 'fetch',
  onDownloadProgress(e) {
    console.log('downloadProgress', e);
  },
  env: {
    fetch,
  },
});

const { data } = await instance.get('https://google.com');

Using with SvelteKit

SvelteKit uses a custom fetch function for server rendering in load functions. It also uses relative paths, which are incompatible with the standard URL API. Configure Faxios to use SvelteKit's custom fetch API:

export async function load({ fetch }) {
  const { data: post } = await faxios.get('https://jsonplaceholder.typicode.com/posts/1', {
    adapter: 'fetch',
    env: {
      fetch,
      Request: null,
      Response: null,
    },
  });

  return { post };
}

Semver

Faxios follows semver since v1.0.0.

Promises

faxios depends on a native ES6 Promise implementation to be supported. If your environment doesn't support ES6 Promises, you can polyfill.

TypeScript

faxios includes TypeScript definitions and a type guard for faxios errors.

let user: User = null;
try {
  const { data } = await faxios.get('/user?ID=12345');
  user = data.userDetails;
} catch (error) {
  if (faxios.isFaxiosError(error)) {
    handleFaxiosError(error);
  } else {
    handleUnexpectedError(error);
  }
}

Use faxios.isCancel<T>() to narrow cancellation errors to CanceledError<T>:

const controller = new AbortController();

try {
  await faxios.get<User>('/user?ID=12345', { signal: controller.signal });
} catch (error) {
  if (faxios.isCancel<User>(error)) {
    handleCancellation(error);
  }
}

faxios is ESM-only. Use "moduleResolution": "node16" or "bundler" in your tsconfig.json.

When using responseSchema, TypeScript infers response.data from the schema's output type automatically — no manual generic needed:

import { z } from 'zod';

const UserSchema = z.object({ name: z.string(), age: z.number() });
const { data } = await faxios.get('/user/1', { responseSchema: UserSchema });
// data is typed as { name: string; age: number }

You can also create a custom instance with typed interceptors:

import faxios, { FaxiosInstance, InternalFaxiosRequestConfig } from '@gcmdev/faxios';

const apiClient: FaxiosInstance = faxios.create({
  baseURL: 'https://api.example.com',
  timeout: 10000,
});

apiClient.interceptors.request.use((config: InternalFaxiosRequestConfig) => {
  // Add auth token
  return config;
});

Online one-click setup

You can use Gitpod, a free online IDE for open source projects, to contribute or run the examples online.

Contributing

Local setup

As a supply-chain hardening measure, this repository ships a project-level .npmrc that sets ignore-scripts=true. This blocks npm lifecycle scripts (preinstall, install, postinstall, prepare) from any direct or transitive dependency when you run