openapi-typescript

openapi-typescript turns OpenAPI 3.0 & 3.1 schemas into TypeScript quickly using Node.js. No Java/node-gyp/running OpenAPI servers necessary.

The code is MIT-licensed and free for use.

Tip: New to OpenAPI? Speakeasy’s Intro to OpenAPI is an accessible guide to newcomers that explains the “why” and “how” of OpenAPI.

• ✅ Supports OpenAPI 3.0 and 3.1 (including advanced features like discriminators)
• ✅ Generate runtime-free types that outperform old school codegen
• ✅ Load schemas from YAML or JSON, locally or remotely
• ✅ Generate types for even huge schemas within milliseconds

Note: OpenAPI 2.x is supported with versions 5.x and previous

👀 See examples

This library requires the latest version of Node.js installed (20.x or higher recommended). With that present, run the following in your project:

npm i -D openapi-typescript typescript

And in your tsconfig.json, to load the types properly:

{
  "compilerOptions": {
+    "module": "ESNext", // or "NodeNext"
+    "moduleResolution": "Bundler" // or "NodeNext"
  }
}

Highly recommended

Also adding the following can boost type safety:

{
  "compilerOptions": {
+    "noUncheckedIndexedAccess": true
  }
}

First, generate a local type file by running npx openapi-typescript, first specifying your input schema (JSON or YAML), and where you’d like the --output (-o) to be saved:

# Local schema
npx openapi-typescript ./path/to/my/schema.yaml -o ./path/to/my/schema.d.ts
# 🚀 ./path/to/my/schema.yaml -> ./path/to/my/schema.d.ts [7ms]

# Remote schema
npx openapi-typescript https://myapi.dev/api/v1/openapi.yaml -o ./path/to/my/schema.d.ts
# 🚀 https://myapi.dev/api/v1/openapi.yaml -> ./path/to/my/schema.d.ts [250ms]

Then in your TypeScript project, import types where needed:

import type { paths, components } from "./my-openapi-3-schema"; // generated by openapi-typescript

// Schema Obj
type MyType = components["schemas"]["MyType"];

// Path params
type EndpointParams = paths["/my/endpoint"]["parameters"];

// Response obj
type SuccessResponse =
  paths["/my/endpoint"]["get"]["responses"][200]["content"]["application/json"]["schema"];
type ErrorResponse =
  paths["/my/endpoint"]["get"]["responses"][500]["content"]["application/json"]["schema"];

From here, you can use these types for any of the following (but not limited to):

• Using an OpenAPI-supported fetch client (like openapi-fetch)
• Asserting types for other API requestBodies and responses
• Building core business logic based on API types
• Validating mock test data is up-to-date with the current schema
• Packaging API types into any npm packages you publish (such as client SDKs, etc.)

View Docs