Best Open-Source API Testing Tools 2026: 6 Options Compared

Open-source API testing tools mostly appeared because teams grew tired of cloud accounts and per-seat pricing in the older clients. The picks here split into desktop clients and command-line runners. Bruno and Yaak store requests as plain files you can commit to git, which fixes the old problem of collections trapped in a vendor account. Insomnia keeps a familiar interface and a plugin system, but pushes you toward a login and paid sync. Hoppscotch runs in the browser or self-hosted, so a team can share without installing anything. Hurl works differently: you write requests and assertions in plain text and run them from the terminal or a pipeline, which fits automated checks better than manual poking. Swagger UI is documentation you can click through, not a full testing client, but it is useful when your API already has an OpenAPI file. The trade-off is licensing. Yaak's source is MIT, yet its prebuilt binaries need a paid license at work after a trial, and some tools gate team features behind a plan. Check that before standardizing a team on one. Pick by how you work: files in git, a browser tab, or a script in continuous integration.

Bruno

MIT desktop client that stores collections as plain files in your repo. The Open Source edition is free; Pro is $6 per user a month, annual billing.

Price: Free (Open Source edition: unlimited collection runner, REST/GraphQL/gRPC, 2 workspaces, Git support for public providers only); paid from $6 per user/month, billed annually (Pro) (Bruno pricing, checked 2026-10-22).

Platforms and license: Windows, macOS, Linux, CLI. MIT (open source) (license source).

Project activity: 47.9k GitHub stars · latest release v4.3.0 (Oct 22, 2026) · last commit Oct 27, 2026

Best for: Teams keeping collections in git.

Worth knowing: Collections are stored as plain files in your repo. Ultimate is $11 per user/month billed annually.

Hoppscotch

MIT web client you can also self-host, with a free plan covering workspaces, collections and a runner. Team features need a paid plan; check the pricing page for current prices.

Price: Free (Free plan with personal workspace, collections, environments and collection runner; no numeric limits listed) (Hoppscotch pricing, checked 2026-10-22).

Platforms and license: Web, Windows, macOS, Linux, CLI. MIT (open source) (license source).

Project activity: 80.7k GitHub stars · latest release 2026.9.0 (Sep 30, 2026) · last commit Oct 26, 2026

Best for: Browser-based sharing.

Insomnia

Apache-2.0 client for REST and GraphQL. Free Essentials includes Git Sync for up to 3 users; Pro is $12 per user a month, with sync pushed toward paid tiers.

Price: Free (Essentials: Git Sync for up to 3 users, unlimited local and cloud projects, 1,000 mock requests per month); paid from $12 per user/month (Pro), annual by default (Insomnia pricing, checked 2026-10-22).

Platforms and license: Windows, macOS, Linux. Apache-2.0 (open source) (license source).

Project activity: 40.1k GitHub stars · latest release core@13.3.1 (Oct 9, 2026) · last commit Oct 27, 2026

Best for: Users who like a familiar interface.

Worth knowing: Enterprise is $45 per user/month for up to 50 self-serve users.

Compare: Insomnia alternatives

Yaak

MIT source with prebuilt binaries free for personal use only. Work use needs a license from $79 a year after a 30-day evaluation.

Price: Free (Free for personal use; a license is required when using it at work (30-day commercial evaluation)); paid from $79 per year (Individual); $399 one-time lifetime; Business $149 per user/year (Yaak pricing, checked 2026-10-22).

Platforms and license: Windows, macOS, Linux. MIT (source); commercial license for prebuilt binaries at work (open source) (license source).

Project activity: 19.4k GitHub stars · latest release v2026.9.0 (Oct 10, 2026) · last commit Oct 27, 2026

Best for: Fast desktop client for personal projects.

Worth knowing: Source is MIT-licensed; licensing applies to the prebuilt binaries.

Hurl

Apache-2.0 command-line tool that runs and tests HTTP requests written in plain text. Ideal for checks inside a CI pipeline, with no graphical interface.

Price: Free (Free open-source software) (Hurl pricing, checked 2026-10-24).

Platforms and license: Command line. Apache-2.0 (open source) (license source).

Project activity: 19.3k GitHub stars · latest release 8.0.1 (Apr 29, 2026) · last commit Oct 27, 2026

Best for: Automated API checks in CI.

Worth knowing: Runs and tests HTTP requests written in plain text files, per the repository description.

Swagger

Swagger UI is Apache-2.0 and lets people try an API from its OpenAPI file. It is documentation first and a weaker testing client than the others.

Price: Free (Swagger pricing, checked 2026-10-23).

Platforms and license: Web. Apache-2.0 (Swagger UI) (open source) (license source).

Project activity: 29.1k GitHub stars · latest release v5.34.0 (Oct 19, 2026) · last commit Oct 27, 2026

Best for: Publishing interactive API docs.

Compare: Swagger alternatives

Which one to pick

• You want requests versioned with your code: Bruno
• Your team wants a shared browser workspace: Hoppscotch
• You need API checks in a pipeline: Hurl
• You need interactive docs from an OpenAPI file: Swagger
• You want a GraphQL-friendly desktop app: Insomnia