TestFiles.dev
Generate precise test files, byte by byte
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TestFiles.dev - Generate precise test files, byte by byte

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Generate exact-size test files directly in your browser, inspect magic bytes and MIME signatures, or download verified MP4, MOV, WebM, PDF and Office samples from stable URLs. Built for upload limits, file validation, media pipelines, and Playwright/Cypress fixtures—no account or upload required.

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Hey Product Hunt — I built TestFiles after repeatedly needing oddly specific fixtures: a 10 KB PNG, a predictable video sample, or a file whose extension did not match its signature. Keeping a random folder of fixtures was hard to trust and even harder to reproduce. TestFiles generates exact-size files locally in the browser and includes an inspector for magic bytes, MIME information, hashes, and extension conflicts. For media and Office workflows, it also provides stable verified sample URLs that work well in automated tests. The main goal is to make upload boundaries and validation failures quick to reproduce without sending generated files to a server. I’d really value feedback from developers and QA engineers: which formats or edge cases would make this more useful in your own test suite?