macOS is more permissive than Windows: the Finder mainly rejects the forward slash / and the colon : (a leftover path separator it still shows as /). Paste a name below and the macOS profile removes those, straightens smart quotes and tidies spaces.
In practice, avoid the forward slash / and the colon :. The Finder blocks both; the profile deletes them.
A name starting with . becomes a hidden file in Finder and the shell, so avoid a leading dot unless you mean it.
macOS allows characters Windows forbids. If the file might travel to a PC or the cloud, use the Windows profile instead for full portability.
Download this exact setup as a ready-made Filename-safe (macOS) profile. Give it a global hotkey in the Windows app and any name you copy is cleaned for this target the instant you paste, so a Windows machine can prepare files for a Mac, a Linux box or a server over SSH. Same engine as above, entirely offline.
In everyday use the Finder rejects two characters: the forward slash / and the colon :. At the lowest level only / and the null character are truly forbidden, but the Finder also blocks : because it is the classic Mac path separator.
The colon was the path separator in classic Mac OS, so macOS still reserves it. If you type a colon in the Finder it is stored as a slash, which is why the profile removes it.
By default no. The standard APFS and HFS+ volumes are case-insensitive but case-preserving, so Report.txt and report.txt are treated as the same name even though the capitals are kept.
Not always. macOS permits characters that Windows forbids, such as the pipe or question mark. If the file will be opened on a PC or synced to cloud storage, clean it with the Windows profile for full portability.
Cleaning for a different system? Use the tabs above, or head back to the Windows filename cleaner or the full tool on the home page.
Remove Special Characters