Frequently Asked Questions

macOS stores Korean filenames in Unicode NFD (decomposed) form. This means each Korean syllable is split into its component jamo. For example, '한' becomes 'ㅎㅏㄴ'. Windows uses NFC (composed) form and doesn't reassemble these jamo, so you see the individual components instead of the complete syllable.

macOS automatically converts filenames to NFD (decomposed Unicode) when saving files. Accented characters like e, u, or n are split into a base character plus a combining mark. When these files reach Windows, the characters may not display correctly because Windows expects NFC (composed) form.

FilenameFixer is completely safe. No files are ever uploaded to any server. All processing happens locally in your web browser using JavaScript. Your files and their contents never leave your device. You can even use the tool offline after the page loads.

NFC (Canonical Decomposition followed by Canonical Composition) stores characters in their composed form — each character is a single code point. NFD (Canonical Decomposition) breaks characters into base characters and combining marks. For example, 'e' in NFC is U+00E9 (one code point), while in NFD it's U+0065 + U+0301 (two code points). Both look the same but are stored differently.

Simply drag and drop your files onto FilenameFixer. The tool will detect NFD-encoded filenames and convert them to NFC. You can then download the files with their corrected names. The file contents remain unchanged — only the filenames are fixed.

Yes! FilenameFixer works with all Unicode characters. It's especially useful for Korean (jamo decomposition), French (accent marks), German (umlauts), Vietnamese (complex diacritics), and Spanish (tilde and accents). It also works with Japanese dakuten, Arabic, Thai, and any other language affected by NFD decomposition.

Apple chose NFD for its file systems (HFS+ and APFS) because decomposed form provides a canonical representation that simplifies string comparison and sorting. While this is technically correct from a Unicode perspective, it creates compatibility issues with Windows and Linux which predominantly use NFC.

You have several options: (1) Use FilenameFixer to convert filenames before sending. (2) Compress files into a ZIP using a tool that converts to NFC. (3) Use cloud services that handle the conversion automatically. (4) Install the FilenameFixer Chrome extension to automatically fix filenames when uploading — and, as the recipient, when downloading.

Yes! You can drag and drop multiple files at once onto FilenameFixer. All filenames will be converted simultaneously. You can download them individually or as a single ZIP file with all the corrected names.

Yes, FilenameFixer is completely free to use with no limits on the number of files or conversions. The tool runs entirely in your browser.

Yes. Open the Fix ZIP page and drop the archive. FilenameFixer rewrites every entry name inside the ZIP from NFD to NFC (Korean jamo are re-joined, accents re-attached) and saves the names with the UTF-8 flag that Windows understands. You download a new ZIP; file contents are copied unchanged and nothing is uploaded.