Yes — designed for it. If the file has nothing to strip, the cleaner passes it through unchanged (or near-unchanged: only whitespace differences from re-serialisation). The page shows it as **ALREADY CLEAN** with a green pill so you know it didn't touch anything important.
If the cleaner can't parse the file at all (broken XML, not really an SVG, encoded as UTF-16, etc.) it surfaces the parser's exact error message and refuses to write a `_clean` version. That's the only failure mode and it's loud — you won't get a silently corrupted file back.
In the live tool, the same logic runs but the cleaned text never leaves your browser tab. If you drop sq.svg into cncfoam.com, the cleaner runs, the tool parses the result, and your original file on disk is untouched. If you also want the cleaned copy on disk, use the standalone https://cncfoam.com/svg_cleaner.php page.
If the cleaner can't parse the file at all (broken XML, not really an SVG, encoded as UTF-16, etc.) it surfaces the parser's exact error message and refuses to write a `_clean` version. That's the only failure mode and it's loud — you won't get a silently corrupted file back.
In the live tool, the same logic runs but the cleaned text never leaves your browser tab. If you drop sq.svg into cncfoam.com, the cleaner runs, the tool parses the result, and your original file on disk is untouched. If you also want the cleaned copy on disk, use the standalone https://cncfoam.com/svg_cleaner.php page.