10 Best Free API Testing Tools in 2025 (Postman Alternatives Included)

API testing used to be synonymous with Postman. Then Postman changed its pricing and syncing model, and developers started looking around. What they found was a surprisingly healthy ecosystem of alternatives — some open source, some lightweight, some designed specifically to avoid the cloud-sync dependencies that made Postman feel heavier than it needed to be. In 2025, the best free API testing tool depends on what you actually need: a full-featured desktop app, something embedded in your editor, a shareable web interface, or a scriptable CLI. This guide covers all of those bases. Quick Comparison Table Tool Type Free Tier Collaboration Collections Scripting Offline Postman Desktop/Web Yes (limited) Yes Yes Yes Partial Insomnia Desktop Yes (local only) Paid Yes Yes Yes Bruno Desktop Fully free Via Git Yes Yes Yes Hoppscotch Web/Self-host Yes Yes (limited) Yes Yes Web only HTTPie Desktop/CLI Free (CLI) No No No Yes Thunder Client VS Code ext Yes No Yes Limited Yes REST Client VS Code ex