LOOK AT THE BYTES, NOT JUST THE NAME

File Signature & Extension Inspector

Identify common file headers, spot extension mismatches and export a batch report without uploading your files. Only the first 4 KB of each file is read.

Choose files to inspect

Drop files here or choose up to 200 files

Large files are supported because only their headers are read. Files are never opened as programs.

Choose files or try the sample. Sample files contain headers only, not complete media.

A matching signature does not prove a file is valid or safe. A mismatch can be an innocent rename. This tool is not an antivirus scanner and does not recommend opening suspicious files.

Name	Size	Detected family	Extension check	Details

Select a result to inspect the first 64 bytes.

How to inspect an unexpected file

Choose files or drop them into the input area. Try sample headers for a safe demonstration.
Compare each detected family with its extension. Inspect shows a MIME suggestion, limitations and the first bytes in hex.
Download a report for your records. Verify suspicious files through your security software; changing an extension does not convert a file.

What the results mean

Compatible means the extension belongs to the detected family. ZIP includes Office documents and EPUB; an archive header cannot confirm its contents. ID3 and EBML indicate container or metadata families, not verified codecs. Unknown formats and plain text may have no signature.

Recognizes common image, archive, media, PDF, SQLite, font, WebAssembly and executable-family headers. It does not parse entire files, extract archives or find hidden payloads.

Using File Signature & Extension Inspector

Compare a file header with its name before deciding which application should handle it.

Choose up to 200 files or drop them into the input area.
Review detected families and extension mismatches; Inspect shows header bytes.
Download the report and independently check suspicious files with your security software.

Example

Try sample headers: a PNG named .jpg, a PDF header, unrecognized text and an empty file.

Questions & answers

Does a matching signature mean my file is safe?

No. It identifies a header pattern only. Malicious or damaged files can contain a normal signature. This is not a malware scanner.

How much of each file is read?

The first 4 KB, with the first 64 bytes available in the detail view. Up to 200 files are inspected sequentially. File size alone does not require reading the entire file.

Why does a Word file show ZIP?

DOCX, XLSX, PPTX, EPUB and several other formats use ZIP containers. Their subtype and internal contents are not verified by header inspection.

Will it change my files?

No. It reads a small slice without writing to the originals or executing their contents. Downloaded reports are separate files.

What does Unknown mean?

No supported signature matched. Plain text, unsupported formats, damaged headers and other files can all produce this result. It is not a safety verdict.