Hoppscotch
FreeOpen-source API client in the browser: REST, GraphQL, WebSocket, SSE and MQTT requests with collections, environments and team workspaces. A lightweight alternative to Postman with a free tier.
Bonus: install Hoppscotch from your browser
Why we recommend Hoppscotch
Hoppscotch is what Postman was before it became an enterprise platform: open the URL, paste an endpoint, send — no mandatory account, no desktop app, no workspace sync nagging. Being MIT-licensed and self-hostable matters for teams whose API collections contain secrets they will not park on a third-party cloud. Protocol coverage (REST, GraphQL with schema introspection, WebSocket, SSE, MQTT) exceeds what most lightweight clients offer.
Best use cases
Best for: quick API smoke tests during development, GraphQL exploration against a live schema, debugging WebSocket streams without writing a throwaway script, and teams that want Postman-style collections on their own infrastructure via the self-hosted edition.
Honest limitations
Browser CORS restrictions block some requests unless you install the browser extension or use the desktop agent — the number-one new-user stumble. Advanced Postman features (mock servers, monitors, heavyweight scripted test suites) are thinner or absent. Team sync beyond small groups moves to paid plans.
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