Best API Development Tools

AI API development tools help you design, build, test, and document APIs faster. From AI-powered test generation to automatic documentation from OpenAPI specs, these tools streamline every stage of the API lifecycle. The category includes API clients, testing platforms, documentation generators, and API design tools used by millions of developers worldwide.

We've evaluated and compared 11 api development tools to help you find the right one for your project. The highest-rated options include ReadMe, Hasura, Postman, and more. 4 of these tools are free or open-source, and 11 offer a free tier so you can try before committing. Each listing includes detailed features, pricing breakdowns, pros and cons, user reviews, and head-to-head comparisons with similar tools.

Last updated: March 2026 · 11 tools compared

Freemium

ReadMe ★ 4.4

Interactive API documentation that developers actually love.

Documentation Generation API Development

Free

Hasura

Freemium

Hasura ★ 4.4

Instant GraphQL and REST APIs for your databases with built-in security.

API Development

Free

Freemium

Postman ★ 4.2

The world's leading API platform, now powered by AI.

API Development

Free

Open Source

Hoppscotch ★ 4.2

Open-source API development ecosystem — lightweight and fast.

API Development

Free

Open Source

Swagger ★ 4.2

The most widely used API documentation and design toolset.

Documentation Generation API Development

Free

Freemium

Redocly ★ 4.2

Beautiful API documentation and developer portals from OpenAPI specs.

Documentation Generation API Development

Free

Open Source

Insomnia ★ 4.2

Open-source API client for REST, GraphQL, gRPC, and WebSocket testing.

API Development

Free

Clerk

Freemium

Clerk ★ 4.2

Modern authentication and user management for developers.

API Development

Free

Open Source

Bruno ★ 4.0

Offline-first, git-friendly API client that stores requests in files.

API Development

Free

Freemium

Thunder Client ★ 3.9

Lightweight REST API client built directly into VS Code.

API Development

Free

Freemium

RapidAPI ★ 3.8

The world's largest API marketplace for discovering and connecting APIs.

API Development

Free