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 https://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 https://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.