How to Use Every Byte of the App Store Keyword Field

Apple's App Store Connect reference says the keywords field accepts up to 100 bytes. Apple's marketing page for product pages says the keywords are limited to 100 characters total (Apple: product page). For basic English letters the two are equal. For other scripts they are not: a character may use two or three bytes. Plan for bytes. See the 100-byte answer.

Apple states keyword terms are separated by commas with no spaces, and spaces separate words only inside a phrase. Four unnecessary spaces cost four bytes, enough for a short word. See spaces after commas.

Japanese characters take three bytes each in this count. A hypothetical list 習慣化,目標設定,日記帳,振り返り has four terms of 3, 4, 3 and 4 characters (each longer than two characters, as Apple requires) and is 45 bytes for 17 characters. A native English list of 45 bytes holds roughly 45 characters. If you copy an English strategy into Japanese you will hit the limit with fewer words. See localizing keywords.

1. Start with your ranked list from prioritizing keywords.
2. Remove words already in the name, subtitle or category. Apple advises against repeating them.
3. Remove plurals of words included in singular, the word "app", generic terms and filler words. Apple lists these as waste. Special characters carry no extra weight.
4. Check every term has more than two characters.
5. Join with commas, no spaces.
6. Count bytes. The free keyword field checker does this.
7. Fill the leftover. If you have 8 bytes left, add the best candidate that fits in 8 including its comma. The keyword field packer suggests fits.

For the hypothetical habit tracker Streakly, with name and subtitle covering habit, tracker, daily, routine and goals:

streak,checklist,reminder,self care,planner,journal,morning is 59 bytes. Adding mindful,wellness,gratitude,focus gives:

streak,checklist,reminder,self care,planner,journal,morning,mindful,wellness,gratitude,focus

That is 92 bytes. The remaining 8 bytes could hold a word of up to seven characters plus its comma, such as calm.

A full field is not a goal by itself. A weak word in the last slot costs nothing but a missed chance, while a wrong word can lower relevance. If you cannot find a good fit, leave bytes unused and keep looking; see spotting dead keywords. The general rules are in the keyword field guide.

Keep a ranked list of the next ten candidates next to the field. When you remove a dead word or a word moves into the subtitle, the replacement is already chosen, and the byte count stays near the limit without hunting for ideas under time pressure.

Optimize covers the keyword field for each language, so you can pack local lists separately. LocalASO adapts keywords into what people type in each country when you choose to localize. See the Optimize docs and the localization docs.