What is this file?
Paste an extension, search for a MIME type, or run the File Signature Checker. FileHint tells you what a file really is, how to open it, and whether it is safe.
- Runs in your browserFiles never leave your device
- 43 signature formatsPDF / ZIP / PE / SQLite and more
- 200 pages liveExtensions, MIME, guides, compare
- Updated 2026-04-23Cited sources, kept current
What you can do with FileHint
Look up an extension
Usage, how to open, risk level, and recommended apps on one page — with OS-by-OS steps.
Look up a MIME type
What Content-Type values do in HTTP, email, and server configuration — with practical behaviour notes.
Verify a file's real format
Inspect leading bytes inside your browser to check whether the extension matches the content. Nothing is uploaded.
Browse by category
Browse all extensions →Regional and community-specific formats
Formats that persist in specific regions, communities, or eras — easy to stumble into and hard to identify.
Recently added and updated
- Extension.avifAV1 Image File Format
A next-generation image format built on the AV1 codec. Smaller files than WebP with support for transparency, HDR, and animation.
- Extension.binGeneric binary
A catch-all extension for raw binary data — firmware images, disk images, ROMs, memory dumps, and so on.
- Extension.docMicrosoft Word 97-2003 Document
The pre-2007 binary Word format (Compound File Binary). Still circulates in government and SMB workflows and carries a high malware-delivery risk because of embedded macros.
- Extension.exeWindows Executable (PE)
A native Windows executable. Double-clicking launches the program. Disguised EXEs are one of the most common malware delivery paths.
- Extension.heicHEIC (High Efficiency Image Container)
The default image format on iPhone cameras. Roughly half the size of JPEG at similar quality, but can be awkward to open outside of Apple platforms.
- Extension.jpgJPEG Image
A lossy compression format optimised for photographs — the default on smartphone cameras and web galleries. `.jpg` and `.jpeg` are identical; the three-letter form is a DOS-era holdover.
- Extension.mp3MPEG-1/2 Audio Layer III
The de-facto standard for music distribution for over 25 years. Playable on virtually anything with a speaker.
- Extension.msiWindows Installer Package
The standard Windows installer container. Holds install, upgrade, repair, and uninstall instructions.
Starting points
- Browse all guides →
Practical guides for opening, verifying, and converting files.
- Browse all comparisons →
Side-by-side comparisons that help you pick the right format.
- Browse all MIME types →
MIME types used by HTTP, email, and server configuration.
- File Signature Checker →
Verify whether an extension matches the real file format — in your browser.