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Build, send, and test API requests with ease.
About this tool
Build, send, and test API requests with ease.
API TESTER is a free developer tool that runs entirely in your browser — nothing to install, no account to create, and your data never leaves your device. Open the page, add your input, and get a clean, copy-ready result in seconds.
Open API TESTER on AltFTool — it loads instantly in your browser.
Paste your code or data sample into the workspace.
Pick the format, conversion, or analysis you need.
Copy the polished result straight back into your project.
Paste snippets, payloads, or commands straight from your editor and get a tidy, shareable result in one step.
Format, convert, or inspect data before it lands in tests, documentation, or production requests.
Use the generated output as a copy-ready starting point instead of writing everything by hand.
Yes — API TESTER is completely free on AltFTool, with no signup, no trial limits, and no hidden costs.
Yes. API TESTER runs in your browser, so what you enter or upload stays on your device instead of being sent to a server.
Build, send, and test API requests with ease. It's built for quick, everyday developer tasks with results you can copy or download straight away.
Yes — API TESTER works in any modern browser, on desktop, tablet, and mobile, with the same features everywhere.