@powerduck/openapi-codegen

Generate runnable HTTP request examples from OpenAPI documents. Supports 21 languages and 41 language/client combinations. Browser-compatible, zero runtime dependencies.

Powerduck is an open-source developer tooling platform for teams building modern API workflows.

• 21 Languages — JavaScript, Python, Go, Rust, Java, PHP, Ruby, C#, F#, Kotlin, Swift, Dart, and more
• 41 Client Combinations — fetch, axios, requests, httpx, http.client, aiohttp, Guzzle, RestSharp, and more
• OpenAPI 3.0/3.1/3.2 — Full support for modern OpenAPI specifications
• Security Schemes — Bearer tokens, API keys, Basic auth, OAuth2, and custom headers
• Parameter Handling — Path, query, header, and cookie parameters with proper encoding
• Request Bodies — JSON, form-data, x-www-form-urlencoded, and raw payloads
• Browser Compatible — Pure TypeScript, no Node.js dependencies, works in any modern browser
• Dual ESM/CJS — Works with import and require, with bundled TypeScript declarations

Quick Start

Install

npm install @powerduck/openapi-codegen

Generate from a document

import { generate } from "@powerduck/openapi-codegen";

const code = generate({
  document: openApiDocument,
  path: "/pets/{id}",
  method: "get",
  language: "javascript",
  client: "fetch",
});

console.log(code);

List available generators

import { list } from "@powerduck/openapi-codegen";

for (const { language, client } of list()) {
  console.log(`${language}/${client}`);
}

Provide credentials

const code = generate({
  document,
  path: "/pets/{id}",
  method: "get",
  language: "javascript",
  client: "fetch",
  securityValues: {
    bearerAuth: "your-token-here",
    apiKey: "your-api-key",
  },
});

Links

• Official Website
• Documentation
• Live Demo
• GitHub
• npm

Supported Languages & Clients

| Language (language) | Clients (client) | | --------------------- | --------------------------------------------------------------- | | c | libcurl | | csharp | httpclient, restsharp | | clojure | clj-http | | dart | http | | fsharp | httpclient | | go | new-request | | http | http1 | | java | asynchttp, java-net-http, okhttp, unirest | | javascript | axios, fetch, jquery, ofetch, xhr | | kotlin | okhttp | | node | axios, fetch, ofetch, undici | | objc | nsurlsession | | ocaml | cohttp | | php | curl, guzzle, laravel-http | | powershell | invoke-restmethod, invoke-webrequest | | python | aiohttp, http-client, httpx-async, httpx-sync, requests | | r | httr2 | | ruby | net-http | | rust | reqwest | | shell | curl, httpie, wget | | swift | nsurlsession |

API Reference

generate(options)

Generate HTTP request code from an OpenAPI document.

import { generate } from "@powerduck/openapi-codegen";

const code = generate({
  document: openApiDocument,
  path: "/pets",
  method: "post",
  language: "python",
  client: "requests",
  securityValues: { bearerAuth: "token" },
});

Options

| Option | Type | Required | Description | | ---------------- | ------------------------ | -------- | ---------------------------------------------------------- | | language | string | Yes | Target language id (see the table above) | | client | string | Yes | HTTP client id (see the table above) | | document | unknown | Yes* | Parsed OpenAPI document object | | path | string | Yes* | API path (e.g. /pets/{id}) | | method | string | Yes* | HTTP method (get, post, put, delete, patch, head, options) | | request | RequestIR | No | Pre-built intermediate request; skips document normalization | | serverUrl | string | No | Override the resolved base URL | | securityValues | Record<string, string> | No | Security scheme values | | softRefMode | boolean | No | Lenient $ref resolution for partially available documents |

* Required when request is not provided. The common path is document + path + method; pass a pre-built request only when you have already normalized the operation yourself.

list()

List all available language/client combinations.

import { list } from "@powerduck/openapi-codegen";

const generators = list();
// [{ language: "javascript", client: "fetch" }, ...]

normalize(options)

Normalize one operation into the intermediate request shape and validate its inputs.

import { normalize } from "@powerduck/openapi-codegen";

const normalized = normalize({
  document: rawDocument,
  path: "/pets/{id}",
  method: "get",
});

TypeScript Types

import type {
  GenerateOptions,
  Generator,
  Parameter,
  Security,
  Body,
} from "@powerduck/openapi-codegen";

Browser Usage

<script type="module">
  import { generate, list } from "https://esm.sh/@powerduck/openapi-codegen";

  const code = generate({
    document: openApiDoc,
    path: "/users",
    method: "get",
    language: "javascript",
    client: "fetch",
  });
</script>

License

MIT © POWERDUCK LIMITED

0.6.4 — Circular parameter values

Serializing a circular deepObject query parameter now throws a descriptive TypeError instead of looping indefinitely. Shared acyclic objects are still serialized at every occurrence.

Extended HTTP methods

HTTP operation discovery includes all nine fixed OpenAPI 3.2 methods (including trace and query) and custom verbs in additionalOperations, such as PROPFIND, REPORT, and CUSTOM-VERB. Shared method helpers come from @powerduck/openapi-parser/methods; path metadata is not interpreted as an operation. Custom verbs must be valid HTTP tokens. Use OpenAPI 3.2 when declaring QUERY or additionalOperations.

Generated requests preserve custom method names. The target HTTP client/server must support the method; browser Fetch restrictions still apply to methods such as CONNECT and TRACE.