Introducing Resend's OpenAPI Spec

Interact with the Resend API using Postman, Insomnia, or any API client of your choice.

Kewyn AkshlleyKewyn Akshlley

To simplify life for developers, we're excited to announce the release of Resend's OpenAPI specification.

This new resource provides a comprehensive map of the API, helping you understand its endpoints, parameters, and response formats.

→ Download the Resend OpenAPI specification or find it in the GitHub repository.

What is OpenAPI?

OpenAPI is an industry-standard format for describing RESTful APIs.

The cool thing about OpenAPI is that it's language-agnostic, meaning that it can be used to describe APIs written in any programming platform.

This allows both humans and machines to understand how an API works in a standardized way and brings an entire ecosystem of tools along with it.

How to use it with Postman?

Instead of creating your own Postman collection, you can import the OpenAPI spec directly into Postman and send requests immediately. Here's how:

  • Choose a workspace and navigate to the collections section.
  • Click "Import" and choose the Resend OpenAPI file (or paste the content).
  • Create an environment variable with a global scope named bearerAuth with your Resend API key.
  • Postman will import the OpenAPI spec and create a new collection for it.

You can also visit the Resend Postman Workspace, where you will find an official collection maintained by the Resend team.

Resend Postman Workspace
Resend Postman Workspace

Because of OpenAPI's interoperability, the same can be done with other API clients like Insomnia and RapidAPI.

Resend Insomnia Collection
Resend Insomnia Collection

What else can you do with OpenAPI?

There's a lot that you can do from a single OpenAPI file, including:

  • Emulate real API calls locally with a mock server.
  • Generate client SDKs for various programming languages.
  • Automate testing, including endpoint validation and payload verification.

As an example, it is now possible to build a strongly-typed Rust library for Resend:

openapi-generator generate -g rust \
  -i https://raw.githubusercontent.com/resend/resend-openapi/main/resend.yaml \
  -o resend-rust

Moving forward

Our goal is to ensure that this Open API specification serves as an accurate representation of the Resend API. Let us know if you find any issues or have any suggestions for improvement.