Filetype Determiner
Works out what a file actually is by reading its first bytes and comparing them against known signatures — completely independent of whatever extension it happens to have.
Drop any file here, or click to choose one
Works entirely offline in your browser. Nothing is uploaded.
When you'd use this
- Figuring out what a file actually is when its extension is missing or wrong
- Verifying a downloaded file matches what it claims to be
- Identifying an unfamiliar file found on an old drive or backup
Checks against a table of common signatures (images, archives, documents, executables, and more). A file can rename its extension to anything; its header bytes rarely lie.