Unicode Normalizer (NFC / NFD / NFKC / NFKD)
Convert text between Unicode normalization forms (NFC, NFD, NFKC, NFKD). It is handy when copied text looks identical but fails to match in search or comparison, for example macOS filenames where a precomposed character is split into a base letter plus a combining mark. To convert full-width and half-width characters by hand, try the Full-width / Half-width Converter.
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Notes
- NFKC and NFKD also replace compatibility characters, so appearance or meaning can change: half-width katakana becomes full-width, full-width letters become ASCII, "①" becomes "1", and so on. If you only want to repair split accents or dakuten, choose NFC.
- Older macOS file systems store filenames in a decomposed (NFD-like) form. Even after you paste normalized text, the destination may decompose it again.
- The list of changes compares each character together with its combining marks as one unit. For long text, only the first 50 changes are listed.
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Glossary
NFC / NFD
NFC merges base characters and combining marks into single characters where possible; NFD splits them apart. For example "é" is one code point in NFC and "e" plus a combining accent in NFD.
NFKC / NFKD
Like NFC and NFD, but they also replace compatibility characters such as half-width katakana, full-width letters, circled digits and ligatures with standard ones. Useful for matching text, but not reversible.
Combining mark
A character drawn on top of the preceding one, such as an accent or the Japanese dakuten (U+3099). A decomposed form looks the same but is a different string.
FAQ
Why do Japanese dakuten split apart in Mac filenames?
Older macOS file systems store filenames in a decomposed (NFD-like) form, such as a base kana plus a combining dakuten. It looks identical but is a different string, so searches and comparisons fail. Converting to NFC merges them.
Should I choose NFC or NFKC?
To repair split dakuten or accents, NFC is enough. NFKC also replaces compatibility characters, such as half-width katakana or full-width letters, so the text can change visibly.
Can the text decompose again after I paste it somewhere?
Yes. If the destination OS or app stores filenames in decomposed form, the pasted text may be split again when saved.
Are emoji and kanji affected?
Most emoji and kanji stay as they are. A few compatibility ideographs are replaced by standard ones in every form, and ligatures and circled digits change under NFKC or NFKD.
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