Filename Cleaner
Make filenames safe across operating systems, and see exactly what was wrong with them.
Processing: This tool runs entirely in your browser. Your input and any file you open stay on your device — nothing is uploaded to a server.
How to use the filename cleaner
- Paste your filenames, one per line.
- Choose how aggressive the cleaning should be.
- Copy the corrected names.
About this tool
Paste a list of filenames and get versions that work everywhere, with each problem named rather than silently corrected.
Several of these failures are genuinely obscure. Windows forbids nine characters outright, which is well known. Less known is that it *silently strips* trailing dots and spaces — so a file saved as `report. ` becomes `report`, and a script looking for the original name will not find it. Less known still, Windows reserves a handful of device names — `CON`, `PRN`, `AUX`, `NUL`, `COM1` through `COM9`, `LPT1` through `LPT9` — regardless of extension, so a file called `con.txt` cannot be created at all.
Accents are reduced to their base letters rather than deleted: `café` becomes `cafe`, not `caf`. That is done by decomposing the character and dropping the combining mark, which is the difference between a readable name and a mangled one.
The extension is preserved separately throughout. Every transform here would otherwise damage it — truncation would cut it off, punctuation stripping would remove the dot that defines it, and a leading dot is correctly treated as a hidden file rather than an extension.
This produces corrected names. It does not rename anything on your computer, which a web page cannot do.
Common uses
- Preparing files for a system that rejects spaces or accents.
- Fixing names before uploading to a web server.
- Finding out why a file will not save on Windows.
Frequently asked questions
- Why can I not create a file called CON.txt?
- Windows reserves CON, PRN, AUX, NUL, COM1-9 and LPT1-9 as device names, regardless of extension. The file cannot be created at all.
- What happens to accented characters?
- They are reduced to their base letters, so café becomes cafe rather than caf. The accent is dropped, not the letter beneath it.
- Does this rename my files?
- No — a web page cannot touch your filesystem. It produces the corrected names for you to apply.
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