Interactive API documentation

Introduces the interactive documentation tool for the GitLab API.

About the OpenAPI specification

The OpenAPI specification (formerly called Swagger) defines a standard, language-agnostic interface to RESTful APIs. OpenAPI definition files are written in the YAML format, which is automatically rendered by the GitLab browser into a more human-readable interface.

For general information about the GitLab APIs, see API Docs.


The interactive API documentation tool allows API testing directly on the website. Only a few of the available endpoints are documented with the OpenAPI spec, but the current list demonstrates the functionality of the tool.

API viewer screenshot

Endpoint parameters

When you expand an endpoint listing, you see a description, input parameters (if required), and example server responses. Some parameters include a default or a list of allowed values.

API viewer screenshot

Starting an interactive session

A Personal access token (PAT) is one way to start an interactive session. To do this, select Authorize from the main page, and a dialog box prompts you to enter your PAT, which is valid for the current web session.

To test the endpoint, first select Try it out on the endpoint definition page. Input the parameters as required, then select Execute. In the following example, we executed a request for the version endpoint (no parameters required). The tool shows the curl command and URL of the request, followed by the server responses that are returned. You can create new responses by editing the relevant parameters and then select Execute once again.

API viewer screenshot


The API code is the single source of truth, and the API documentation should be tightly coupled to its implementation. The OpenAPI specification provides a standardized and comprehensive way to document APIs. It should be the go-to format for documenting the GitLab REST API. This will result in more accurate, reliable, and user-friendly documentation that enhances the overall experience of using the GitLab REST API.

To achieve this it should be a requirement to update the OpenAPI specification with every API code change. By doing so, we ensure that the documentation is always up-to-date and accurate, reducing the risk of confusion as well as errors for our users.

The OpenAPI documentation should be autogenerated from the API code, so that it is easy to keep it up to date and accurate. This will save time and effort for our documentation team.

You can follow the current progress of this vision in the Document the REST API in OpenAPI V2 epic.