Identify a file
Choose or drop a file. Its first bytes are read in your browser and compared with the signatures of every known format; nothing is uploaded.
…or drop it anywhere on this box.
A signature match is reliable; a match on the extension alone is a guess, since many formats share one (.dat, .bin). Signatures here are fixed prefixes, so related formats (PNG and APNG) can tie: the format page tells them apart.