# Source: https://docs.apify.com/api/v2/act-openapi-json-get.md

# Get OpenAPI definition


```
GET 
https://api.apify.com/v2/acts/:actorId/builds/:buildId/openapi.json
```


Get the OpenAPI definition for Actor builds. Two similar endpoints are available:

* [First endpoint](https://docs.apify.com/api/v2/act-openapi-json-get.md): Requires both `actorId` and `buildId`. Use `default` as the `buildId` to get the OpenAPI schema for the default Actor build.

* [Second endpoint](https://docs.apify.com/api/v2/actor-build-openapi-json-get.md): Requires only `buildId`.

Get the OpenAPI definition for a specific Actor build.

To fetch the default Actor build, simply pass `default` as the `buildId`. Authentication is based on the build's unique ID. No authentication token is required.

note

You can also use the [/api/v2/actor-build-openapi-json-get](https://docs.apify.com/api/v2/actor-build-openapi-json-get.md) endpoint to get the OpenAPI definition for a build.

## Request

## Responses

* 200
* 400

**Response Headers**



Bad request - invalid input parameters or request body.