Identify a file type from its first bytes, or look up the magic signature of an extension — 30+ signatures built in.
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Look up by extension
Either drop a file (only the first 16 bytes are read into memory) or paste hex bytes — with or without spaces, any case — and click Detect. The tool matches the leading bytes against a built-in table of ~30 common file signatures (PNG, JPG, GIF, PDF, ZIP, RAR, 7z, MP4, WebP, BMP, ICO, GZIP, TAR, SQLITE, Office OOXML docx/xlsx/pptx, etc.), showing the detected file type, MIME and a short description. If nothing matches, the raw hex is shown marked Unknown. The second panel lets you pick an extension and see the magic bytes you'd expect.