openapi-typescript/README.md

Convert OpenAPI 3.0 & 3.1 schemas to TypeScript

<img src="../../docs/public/assets/openapi-ts.svg" alt="openapi-typescript" width="200" height="40" />

openapi-typescript turns [OpenAPI 3.0 & 3.1](https://spec.openapis.org/oas/latest.html) schemas into TypeScript quickly using Node.js. No Java/node-gyp/running OpenAPI servers necessary.

The code is [MIT-licensed](./LICENSE) and free for use.

> **Tip:**
> New to OpenAPI? Speakeasy’s [Intro to OpenAPI](https://www.speakeasyapi.dev/openapi) is an accessible guide to newcomers that explains the “why” and “how” of OpenAPI.

## Features

- ✅ Supports OpenAPI 3.0 and 3.1 (including advanced features like [discriminators](https://spec.openapis.org/oas/v3.1.0#discriminator-object))
- ✅ 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_

## Examples

👀 [See examples](./examples/)

## Setup

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

```bash
npm i -D openapi-typescript typescript
```

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

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

> **Highly recommended**
> 
> Also adding the following can boost type safety:
> ```diff
> {
>   "compilerOptions": {
> +    "noUncheckedIndexedAccess": true
>   }
> }
> ```

## Basic usage

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:

```bash
# 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:

```ts
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](https://openapi-ts.dev/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.)

## 📓 Docs

[View Docs](https://openapi-ts.dev/)