Magic Number Reference
Identify a likely file format from its leading bytes, or search a curated table of file signatures by name or extension.
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Result
How it works
Paste the first few bytes of a file as hex to see which format signatures match, or type a format name or extension to browse the table. Signatures come from the format specifications and the file(1) magic database (checked 2026-09-01). A match is a strong hint, not proof: ZIP backs docx/xlsx/jar/apk/epub, RIFF backs WAV/WebP/AVI, and CAFEBABE is both a Java class and a Mach-O fat binary. Only the first 512 bytes (one tar header block, enough to reach the ustar magic at offset 257) are examined and nothing is transmitted. Use the ELF and PE header tools for a structural breakdown of executables.