5 Free Developer Tools for API Testing and Debugging
These tools are free, powerful, and criminally underused. If you write code, build APIs, or work with data — bookmark these.
Published March 16, 2026
1
Hoppscotch
hoppscotch.io
Open-source API development ecosystem that runs entirely in your browser.
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Regex101
regex101.com
Real-time regex tester with explanation, debugger, and community library.
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Devdocs.io
devdocs.io
Unified API documentation browser with instant search across 500+ docs.
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Observable
observablehq.com
Reactive JavaScript notebooks for data visualization and analysis.
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Excalidraw
excalidraw.com
Virtual whiteboard for hand-drawn style diagrams and collaboration.
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