Purpose
Extensions alone are not enough for uploads, previews, conversion, security checks, or data migration. This site focuses on leading bytes, container structure, and real samples you can download to test implementation behavior.
Data
- The site currently lists 50 formats and 542 sample files.
- Format pages focus on signatures, MIME types, structure, caveats, and detection examples.
- Sample files are generated in-house or based on public-domain, CC0, or otherwise usable sources.
Sample policy
Samples are designed to be safe, explainable, and useful for file detection, parser tests, previews, download handling, and file-size boundary checks.
Every sample lists its license and SHA-256 hash. In-house generated samples are published as CC0 1.0 unless a more specific source license is shown.
Contact
Use the contact form to report format errors, request new sample files, or ask about source attribution and licensing.