App Store optimization: a practical guide for app founders

What ASO is, and why it compounds

App Store optimization (ASO) is the work of making your app show up, and get chosen, when people search the App Store. It has two halves: ranking for the right searches, and converting the people who see your listing into installs.

Unlike ads, ranking keeps paying off. A keyword you climb into the top five for keeps bringing installs every day without new spend, which is why ASO is usually the first growth channel worth getting right.

The fields Apple indexes, and their limits

Only a few fields on the App Store decide which searches your app can rank for. Each one is short, so every character counts.

• App name: up to 30 characters. The strongest ranking signal. Keep your brand first, then a short description of what the app does.
• Subtitle: up to 30 characters, shown under the name. Also indexed, and also what people read first in search results.
• Keyword field: up to 100 characters, hidden from users. Comma-separated, no spaces after commas.
• Promotional text: up to 170 characters. Not used for ranking, but you can change it any time without a new app version, which makes it ideal for launches and offers.
• Description: up to 4,000 characters. Not used for ranking on the App Store; it's there to convince people who tap through.

How to choose keywords you can actually win

A good keyword has three things: people search for it, it truly describes your app, and the apps ranking for it are beatable. Popular words dominated by giant apps will keep you on page five no matter how well you write.

Start with the words your users use, not the ones you use internally. Read your reviews and your competitors' reviews: the phrases people repeat are usually the phrases they search. Then check volume and difficulty, and favor searches where you already rank between roughly 10 and 50. Those are the fastest wins.

• Look at the searches you already rank for, and where.
• List the searches your direct competitors rank for and you don't.
• Keep terms with real volume and difficulty you can beat.
• Drop anything that doesn't describe what your app actually does.

Writing the keyword field without wasting space

The 100-character keyword field is where most listings leak value. Apple already indexes your name and subtitle, so repeating those words in the keyword field gives you nothing.

• Don't repeat words that are already in your name or subtitle.
• Use singular forms; there's no need to add both singular and plural.
• Separate with commas and no spaces: every space is a lost character.
• Skip words like “app” and your category name; they're covered already.
• Never use competitors' brand names or trademarks. App Review can reject the update for it.

Localize for each market, don't just translate

Each App Store country can have its own listing, and people in each market search in their own words. A literal translation often misses the phrase locals actually type. Writing natively for each market's searches is one of the cheapest ways to reach new users.

Some countries also index more than one language, so a second localization can give you extra keyword space in your main market. Check Apple's current list before relying on it.

Measure, then repeat

Change one thing at a time where you can, and give it a couple of weeks: rankings move gradually. Track the searches you targeted, your impressions and your conversion rate in App Store Connect, and keep what works.

ASO isn't a one-time task. Competitors change their listings, new searches appear and seasons shift what people look for. A short review every month or two keeps you ahead.