Reads the first bytes of a file and tells you what it really is, which is the fix for files that were renamed.
What you get
- Magic-byte report
- Suggests the correct extension
- No upload, runs locally
It runs on the machine you are on — nothing is uploaded, nothing is installed, and the file is not rewritten. Version 3.4.2.
When it is the wrong tool
If the file is corrupt rather than mis-named, this tool will tell you which one it is and nothing more; repair is a separate step.
Checked 2026-10-05 — M. Halvorsen.
What this tool does not do
It reads a file, reports what the first bytes say, and stops there. It does not rename the file, it does not repair it, and nothing is written back to disk unless a page says it is. The report is the whole of the operation.
Tools in this section are rebuilt with each release, and the catalogue they work from is the same one the format pages are built from, so a tool and a format page cannot disagree about a header. The version named on this page is the version in the current build.