Loading page
About this tool
Compare a local file's leading magic bytes with its extension and browser-reported MIME type without uploading the file.
File Signature Verifier is a free security & privacy 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 File Signature Verifier on AltFTool — it loads instantly in your browser.
Upload or drag in the file you want to work with.
Adjust the settings and preview the result.
Download the finished file to your device.
Process images, audio, video, and documents directly in your browser — files never leave your device.
See the result before you export, so the final file is exactly what you expect.
Download output that's ready for your website, presentation, or client hand-off.
Yes — File Signature Verifier is completely free on AltFTool, with no signup, no trial limits, and no hidden costs.
Yes. File Signature Verifier runs in your browser, so what you enter or upload stays on your device instead of being sent to a server.
Compare a local file's leading magic bytes with its extension and browser-reported MIME type without uploading the file. It's built for quick, everyday security & privacy tasks with results you can copy or download straight away.
Yes — File Signature Verifier works in any modern browser, on desktop, tablet, and mobile, with the same features everywhere.