Finch TypeScript API Library

This library provides convenient access to the Finch REST API from server-side TypeScript or JavaScript.

The REST API documentation can be found on developer.tryfinch.com. The full API of this library can be found in api.md.

It is generated with Stainless.

Installation

npm install @tryfinch/finch-api

Usage

The full API of this library can be found in api.md.

import Finch from '@tryfinch/finch-api';

const client = new Finch({
  accessToken: 'My Access Token',
});

const page = await client.hris.directory.list();
const individualInDirectory = page.individuals[0];

console.log(individualInDirectory.id);

Request & Response types

This library includes TypeScript definitions for all request params and response fields. You may import and use them like so:

import Finch from '@tryfinch/finch-api';

const client = new Finch({
  accessToken: 'My Access Token',
});

const [individualInDirectory]: [Finch.HRIS.IndividualInDirectory] = await client.hris.directory.list();

Documentation for each method, request param, and response field are available in docstrings and will appear on hover in most modern editors.

Handling errors

When the library is unable to connect to the API, or if the API returns a non-success status code (i.e., 4xx or 5xx response), a subclass of APIError will be thrown:

const company = await client.hris.company.retrieve().catch(async (err) => {
  if (err instanceof Finch.APIError) {
    console.log(err.status); // 400
    console.log(err.name); // BadRequestError
    console.log(err.headers); // {server: 'nginx', ...}
  } else {
    throw err;
  }
});

Error codes are as follows:

| Status Code | Error Type | | ----------- | -------------------------- | | 400 | BadRequestError | | 401 | AuthenticationError | | 403 | PermissionDeniedError | | 404 | NotFoundError | | 422 | UnprocessableEntityError | | 429 | RateLimitError | | >=500 | InternalServerError | | N/A | APIConnectionError |

Retries

Certain errors will be automatically retried 2 times by default, with a short exponential backoff. Connection errors (for example, due to a network connectivity problem), 408 Request Timeout, 409 Conflict, 429 Rate Limit, and >=500 Internal errors will all be retried by default.

You can use the maxRetries option to configure or disable this:

// Configure the default for all requests:
const client = new Finch({
  maxRetries: 0, // default is 2
});

// Or, configure per-request:
await client.hris.directory.list({
  maxRetries: 5,
});

Timeouts

Requests time out after 1 minute by default. You can configure this with a timeout option:

// Configure the default for all requests:
const client = new Finch({
  timeout: 20 * 1000, // 20 seconds (default is 1 minute)
});

// Override per-request:
await client.hris.directory.list({
  timeout: 5 * 1000,
});

On timeout, an APIConnectionTimeoutError is thrown.

Note that requests which time out will be retried twice by default.

Auto-pagination

List methods in the Finch API are paginated. You can use the for await … of syntax to iterate through items across all pages:

async function fetchAllIndividualInDirectories(params) {
  const allIndividualInDirectories = [];
  // Automatically fetches more pages as needed.
  for await (const individualInDirectory of client.hris.directory.list()) {
    allIndividualInDirectories.push(individualInDirectory);
  }
  return allIndividualInDirectories;
}

Alternatively, you can request a single page at a time:

let page = await client.hris.directory.list();
for (const individualInDirectory of page.individuals) {
  console.log(individualInDirectory);
}

// Convenience methods are provided for manually paginating:
while (page.hasNextPage()) {
  page = await page.getNextPage();
  // ...
}

Default Headers

We automatically send the Finch-API-Version header set to 2020-09-17.

If you need to, you can override it by setting default headers on a per-request basis.

Be aware that doing so may result in incorrect types and other unexpected or undefined behavior in the SDK.

import Finch from '@tryfinch/finch-api';

const client = new Finch();

const page = await client.hris.directory.list({ headers: { 'Finch-API-Version': 'My-Custom-Value' } });
const individualInDirectory = page.individuals[0];

Webhook Verification

We provide helper methods for verifying that a webhook request came from Finch, and not a malicious third party.

You can use finch.webhooks.verifySignature(body: string, headers, secret?) -> void or finch.webhooks.unwrap(body: string, headers, secret?) -> Payload, both of which will raise an error if the signature is invalid.

Note that the "body" parameter must be the raw JSON string sent from the server (do not parse and re-stringify it). The .unwrap() method will automatically parse this JSON for you into a typed Payload.

For example:

// with Express:
app.use('/webhooks/finch', bodyParser.text({ type: '*/*' }), function (req, res) {
  const payload = finch.webhooks.unwrap(req.body, req.headers, process.env['FINCH_WEBHOOK_SECRET']); // env var used by default; explicit here.
  console.log(payload);
  res.json({ ok: true });
});

// with Next.js (app router):
export default async function POST(req) {
  const body = await req.text(); // if you're using the pages router, you will need this trick: https://vancelucas.com/blog/how-to-access-raw-body-data-with-next-js/
  const payload = finch.webhooks.unwrap(body, req.headers, process.env['FINCH_WEBHOOK_SECRET']); // env var used by default; explicit here.
  console.log(payload);
  return NextResponse.json({ ok: true });
}

Advanced Usage

Accessing raw Response data (e.g., headers)

The "raw" Response returned by fetch() can be accessed through the .asResponse() method on the APIPromise type that all methods return. This method returns as soon as the headers for a successful response are received and does not consume the response body, so you are free to write custom parsing or streaming logic.

You can also use the .withResponse() method to get the raw Response along with the parsed data. Unlike .asResponse() this method consumes the body, returning once it is parsed.

const client = new Finch();

const response = await client.hris.directory.list().asResponse();
console.log(response.headers.get('X-My-Header'));
console.log(response.statusText); // access the underlying Response object

const { data: page, response: raw } = await client.hris.directory.list().withResponse();
console.log(raw.headers.get('X-My-Header'));
for await (const individualInDirectory of page) {
  console.log(individualInDirectory.id);
}

Logging

[!IMPORTANT] All log messages are intended for debugging only. The format and content of log messages may change between releases.

Log levels

The log level can be configured in two ways:

1. Via the FINCH_LOG environment variable
2. Using the logLevel client option (overrides the environment variable if set)

import Finch from '@tryfinch/finch-api';

const client = new Finch({
  logLevel: 'debug', // Show all log messages
});

Available log levels, from most to least verbose:

• 'debug' - Show debug messages, info, warnings, and errors
• 'info' - Show info messages, warnings, and errors
• 'warn' - Show warnings and errors (default)
• 'error' - Show only errors
• 'off' - Disable all logging

At the 'debug' level, all HTTP requests and responses are logged, including headers and bodies. Some authentication-related headers are redacted, but sensitive data in request and response bodies may still be visible.

Custom logger

By default, this library logs to globalThis.console. You can also provide a custom logger. Most logging libraries are supported, including pino, winston, bunyan, consola, signale, and @std/log. If your logger doesn't work, please open an issue.

When providing a custom logger, the logLevel option still controls which messages are emitted, messages below the configured level will not be sent to your logger.

import Finch from '@tryfinch/finch-api';
import pino from 'pino';

const logger = pino();

const client = new Finch({
  logger: logger.child({ name: 'Finch' }),
  logLevel: 'debug', // Send all messages to pino, allowing it to filter
});

Making custom/undocumented requests

This library is typed for convenient access to the documented API. If you need to access undocumented endpoints, params, or response properties, the library can still be used.

Undocumented endpoints

To make requests to undocumented endpoints, you can use client.get, client.post, and other HTTP verbs. Options on the client, such as retries, will be respected when making these requests.

await client.post('/some/path', {
  body: { some_prop: 'foo' },
  query: { some_query_arg: 'bar' },
});

Undocumented params

To make requests using undocumented parameters, you may use // @ts-expect-error on the undocumented parameter. This library doesn't validate at runtime that the request matches the type, so any extra values you send will be sent as-is.

client.hris.directory.list({
  // ...
  // @ts-expect-error baz is not yet public
  baz: 'undocumented option',
});

For requests with the GET verb, any extra params will be in the query, all other requests will send the extra param in the body.

If you want to explicitly send an extra argument, you can do so with the query, body, and headers request options.

Undocumented properties

To access undocumented response properties, you may access the response object with // @ts-expect-error on the response object, or cast the response object to the requisite type. Like the request params, we do not validate or strip extra properties from the response from the API.

Customizing the fetch client

By default, this library expects a global fetch function is defined.

If you want to use a different fetch function, you can either polyfill the global:

import fetch from 'my-fetch';

globalThis.fetch = fetch;

Or pass it to the client:

import Finch from '@tryfinch/finch-api';
import fetch from 'my-fetch';

const client = new Finch({ fetch });

Fetch options

If you want to set custom fetch options without overriding the fetch function, you can provide a fetchOptions object when instantiating the client or making a request. (Request-specific options override client options.)

import Finch from '@tryfinch/finch-api';

const client = new Finch({
  fetchOptions: {
    // `RequestInit` options
  },
});

Configuring proxies

To modify proxy behavior, you can provide custom fetchOptions that add runtime-specific proxy options to requests:

Node [docs]

import Finch from '@tryfinch/finch-api';
import * as undici from 'undici';

const proxyAgent = new undici.ProxyAgent('http://localhost:8888');
const client = new Finch({
  fetchOptions: {
    dispatcher: proxyAgent,
  },
});

Bun [docs]

import Finch from '@tryfinch/finch-api';

const client = new Finch({
  fetchOptions: {
    proxy: 'http://localhost:8888',
  },
});

Deno [docs]

import Finch from 'npm:@tryfinch/finch-api';

const httpClient = Deno.createHttpClient({ proxy: { url: 'http://localhost:8888' } });
const client = new Finch({
  fetchOptions: {
    client: httpClient,
  },
});

Frequently Asked Questions

Semantic versioning

This package generally follows SemVer conventions, though certain backwards-incompatible changes may be released as minor versions:

1. Changes that only affect static types, without breaking runtime behavior.
2. Changes to library internals which are technically public but not intended or documented for external use. (Please open a GitHub issue to let us know if you are relying on such internals.)
3. Changes that we do not expect to impact the vast majority of users in practice.

We take backwards-compatibility seriously and work hard to ensure you can rely on a smooth upgrade experience.

We are keen for your feedback; please open an issue with questions, bugs, or suggestions.

Requirements

TypeScript >= 4.9 is supported.

The following runtimes are supported:

• Node.js 20 LTS or later (non-EOL) versions.

• Deno v1.28.0 or higher.

• Bun 1.0 or later.

• Cloudflare Workers.

• Vercel Edge Runtime.

• Jest 28 or greater with the "node" environment ("jsdom" is not supported at this time).

• Nitro v2.6 or greater.

• Web browsers: disabled by default to avoid exposing your secret API credentials. Enable browser support by explicitly setting dangerouslyAllowBrowser to true'.

  Why is this dangerous?

  Enabling the dangerouslyAllowBrowser option can be dangerous because it exposes your secret API credentials in the client-side code. Web browsers are inherently less secure than server environments, any user with access to the browser can potentially inspect, extract, and misuse these credentials. This could lead to unauthorized access using your credentials and potentially compromise sensitive data or functionality.

  When might this not be dangerous?

  In certain scenarios where enabling browser support might not pose significant risks:

  • Internal Tools: If the application is used solely within a controlled internal environment where the users are trusted, the risk of credential exposure can be mitigated.
  • Public APIs with Limited Scope: If your API has very limited scope and the exposed credentials do not grant access to sensitive data or critical operations, the potential impact of exposure is reduced.
  • Development or debugging purpose: Enabling this feature temporarily might be acceptable, provided the credentials are short-lived, aren't also used in production environments, or are frequently rotated.

Note that React Native is not supported at this time.

If you are interested in other runtime environments, please open or upvote an issue on GitHub.

Contributing

See the contributing documentation.