Best Open Source API Development & Testing Tools in 2026
Tools for designing, testing, documenting, and managing APIs used by developers and engineering teams.
6 open source api development & testing tools β ranked by GitHub stars. Browse all
Hoppscotch
Open source API development ecosystem - https://hoppscotch.io (open-source alternative to Postman, Insomnia)
Bruno
Opensource IDE For Exploring and Testing API's (lightweight alternative to Postman/Insomnia)
Insomnia
The open-source, cross-platform API client for GraphQL, REST, WebSockets, SSE and gRPC. With Cloud, Local and Git storage.
HTTPie
π HTTPie Desktop β cross-platform API testing client for humans. Painlessly test REST, GraphQL, and HTTP APIs.
Yaak
The most intuitive desktop API client. Organize and execute REST, GraphQL, WebSockets, Server Sent Events, and gRPC π¦¬
Scalar
Scalar is an open-source API platform:γγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγπ Modern Rest API Clientγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγπ Beautiful API Referencesγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγγβ¨ 1st-Class OpenAPI/Swagger Support