Free Online File Type Identifier Tool

1. Click Choose file and pick any file.
2. Read the detected type, description and typical extension.
3. Compare the first 16 bytes (shown in hex) against the signature to verify.
4. Use the result to spot mismatched extensions before opening unknown files.

File extensions can lie. Someone can rename malware.exe to invoice.pdf and the OS will trust the extension; a renamed-MP3 image saved by some software has no useful extension at all. The reliable way to identify a format is the magic bytes — a short, well-known sequence at the start of the file that's part of the format specification.

Security-conscious users verify an attachment before opening it. Developers debugging upload pipelines confirm what was actually sent versus what the form claimed. Digital archivists identify files in legacy directories with missing extensions. This tool ships signatures for the common formats people deal with day to day: PNG, JPEG, GIF, BMP, WebP, TIFF, ICO, PDF, ZIP, RAR, GZIP, 7z, MP3, WAV, AVI, MP4, FLAC, OGG, EXE, ELF, Mach-O, SQLite.

It reads only the first 16 bytes — your files don't leave your device — and reports the detected name, description and typical extension. Container-based formats like DOCX and XLSX appear as ZIP because that's what they fundamentally are.