App Store keywords best practices: the 100-character field

The best practices for App Store keywords are simple to state: fill all 100 characters with single, relevant words separated by commas and no spaces, never repeat a word already in your title or subtitle, and skip competitor names, trademarks and filler like "app" or "free". Then check what actually ranks after each release and replace the words that brought nothing. Everything below is the detail behind those rules, from running ASO for our own three apps and for client apps alongside close to $100,000 a month in Apple Search Ads.

What the keyword field is and how the store reads it

The keyword field is a hidden 100-character box in App Store Connect, one per localization. Shoppers never see it. The App Store uses it, together with your app name and subtitle, to decide which searches your app can appear for. Apple describes this in its guide to App Store search.

Three facts shape every decision about the field:

• It is small. 100 characters, commas included, is roughly 12 to 18 words.
• It is slow to change. Keywords are part of the version metadata, so you can only edit them when you submit a new version.
• It works in combination. The store matches searches against words from the title, subtitle and keyword field together. A search for "bedtime story" can match an app with "bedtime" in the subtitle and "story" in the keyword field.

That third point is the reason most of the rules below exist. You are not writing a list of phrases. You are supplying building blocks.

The format rules that save characters

These are mechanical, and getting them wrong wastes a fifth of the field on most pages we audit.

1. Commas, no spaces. Write story,bedtime,kids,voice, not story, bedtime, kids, voice. Spaces cost characters and add nothing.
2. Single words, not phrases. "bedtime,story" covers "bedtime story", "story bedtime" and both words combined with terms from your title. "bedtime story" as one entry spends the same characters and covers less.
3. No repeats. If a word is in your title or subtitle, it is already indexed. Repeating it in the field ranks nothing new. This is the same rule we apply to the subtitle in the 30 characters that decide your app's future.
4. No category name. Your primary category is already attached to the app. Spending characters on it is usually redundant.
5. Mind plurals. In our accounts the singular form usually covers the plural for English terms. Add the plural only if you check and it does not rank.
6. Use every character. An unused character is a free ranking you gave away. Leftover space is where you test new words.

What to leave out

Some words look tempting and cost you more than they earn.

• Competitor names and trademarks. App Review guideline 2.3.7 asks developers not to pack metadata with trademarked terms, popular app names or irrelevant phrases. Besides the review risk, in our experience a brand-new app rarely ranks for an established competitor's name. If you want that traffic, bid on it in Apple Search Ads, where it is allowed and measurable.
• "App", "free", "best", "new". These are either implied, unbelievable or both. They rarely decide a search.
• Your own developer name. Searches for it already find you.
• Words that describe a feature you do not have. You might rank, but the people who tap through will not install, and a low conversion rate on a search term works against you.

How to choose the words that go in

Format is the easy half. The hard half is deciding which 15 words deserve the space. We work in four steps.

Start from the search bar. Type the problem your app solves into the App Store search bar and write down the suggestions. Autocomplete shows what people actually type, in their words, not yours.

Check popularity and competition. Apple Search Ads shows a search popularity score for terms in its keyword tools, which is the only first-party demand signal Apple gives you. For each candidate, also search it yourself: if the first ten results are giant apps with tens of thousands of ratings, a new app will struggle there. We explain the full process in Apple Search Ads keyword research from zero, and the same list feeds both ads and ASO.

Map words to fields by weight. The strongest term goes in the title, the next in the subtitle, and the long tail goes into the keyword field. The keyword field is for the words that matter but would not read naturally in front of a shopper.

Fill the gaps between combinations. Look at the phrases you want to rank for and ask which single words are missing. If your title has "stories" and you want "sleep stories" and "stories for toddlers", the field needs "sleep" and "toddler", not the full phrases.

App Store keywords examples

The examples below are illustrations for a fictional bedtime story app, not the metadata of any real listing, ours included. They show the same budget spent badly and well.

The better version leaves the title and subtitle to carry "bedtime" and "stories" and spends the field on words that combine with them: "sleep stories", "fairy tale", "read aloud", "bedtime routine". The wasteful version ranks for fewer searches with more characters.

A second pattern we use often: when a feature has two common names, put one in the subtitle and the other in the field. People search the same thing in different words, and you only need each word once.

Localization doubles the field

Each localization in App Store Connect has its own 100-character keyword field. That means every language you add is another field to fill, and translating your English keywords word for word is the most common way to waste it. Search terms in another market are often a different concept, not a translation. We cover how to find them in the markets most apps ignore.

How to check whether your keywords work

The field is a hypothesis until a release proves it. After each update, give the store some days to reindex, then check three things:

1. Rankings. Search each important term on a device and note your position. A keyword tool does this at scale, but a spreadsheet works for 20 terms.
2. App Analytics. In App Store Connect, look at impressions and product page views from App Store search. A good keyword change shows up there first.
3. Apple Search Ads search terms. If you run Search Match, the search terms report shows real queries that led to taps and installs. Words that convert there are candidates for the field; words in the field that never appear anywhere are candidates to replace.

Change a few words per release, not the whole field. If you rewrite everything at once, you will not know which change moved the numbers. Our 20-minute ASO audit includes the keyword field check if you want a quick pass on the rest of the page too.

Good keyword practice is mostly discipline: single words, no repeats, no filler, and a review after every release. The words themselves come from what people type, which is why we run ASO and Apple Search Ads from the same keyword list. If you want us to look at your field and the page around it, the written audit is free.