The Apple keyword field is 100 bytes, not 100 characters
One of the most common App Store Optimization mistakes is treating the iOS keyword field as a 100-character limit. It is a 100-BYTE limit, measured in UTF-8. For plain English that looks the same, but the moment you use accented, CJK, or emoji characters, your real budget shrinks fast.
Why bytes and not characters?
App Store Connect stores the keyword field as UTF-8. In UTF-8, an ASCII letter is 1 byte, most accented Latin characters are 2 bytes, and Chinese/Japanese/Korean characters and emoji are 3-4 bytes. So '日本語' is 3 characters but 9 bytes: nearly a tenth of your entire budget for three characters.
How do I count it correctly?
Count the UTF-8 byte length, not the string length. In JavaScript that is Buffer.byteLength(value, 'utf8'), not value.length. A validator that uses .length will tell you a CJK keyword set fits when it actually overflows, and App Review will silently truncate it.
Do commas and spaces count?
Commas count as 1 byte each and you do not need spaces: 'fitness,workout,running' is correct, not 'fitness, workout, running'. Never repeat words that already appear in your app name or subtitle: Apple indexes those separately, so duplicating them in the keyword field wastes bytes for zero ranking benefit.
Treat the limit as a constant, not a hardcode
Store the byte limit as a configurable value. The stores adjust their fields over time, and you want one place to change it rather than scattered magic numbers. appusula's metadata editor validates the field live by UTF-8 byte length and warns on duplicates and over-budget input as you type.
FAQ
Is the iOS keyword field 100 characters or 100 bytes?
100 bytes of UTF-8. ASCII letters are 1 byte; accented Latin characters are 2 bytes; CJK characters and emoji are 3-4 bytes.
Should I put spaces after commas in the keyword field?
No. Use single commas with no spaces; spaces waste bytes. 'a,b,c' not 'a, b, c'.
Should I repeat my app name in the keyword field?
No. Apple already indexes your app name and subtitle. Repeating those words in the keyword field wastes bytes without improving rank.
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