You can build a great iOS app and still get almost no downloads, because nobody finds it. App Store Optimization (ASO) is the work of making your app easy to find in App Store search and convincing once someone lands on your product page. It costs nothing but time, and every improvement keeps working while you sleep.
This is the pillar guide. It covers how App Store search works, which fields Apple actually reads, what moves people to tap Get, and how to measure it all. Where a topic deserves a deep dive, you'll find a link to a dedicated guide.
What ASO is (and what it isn't)
ASO has two halves that feed each other:
- Discovery. Showing up when people search for the problem your app solves. This is mostly about the words in your metadata and how relevant Apple thinks your app is for a query.
- Conversion. Turning a search result or product page view into a download. This is about your icon, screenshots, preview video, ratings and the first lines of text people read.
They are linked. Apple says search results are based on text relevance and user behavior, such as downloads and ratings (Apple, App Store search). A listing that converts well sends better signals, which can help it rank, which brings more impressions to convert.
ASO is not keyword stuffing, buying fake reviews or copying a competitor's name into your keywords. Those tactics break the App Review Guidelines (see 2.3.7 on metadata and the Section 3 introduction on manipulated reviews) and can get an update rejected or worse.
How App Store search works
Apple doesn't publish its ranking algorithm, but it does tell developers what goes into it. According to Apple's search guidance, results are based on:
- Text relevance: matches between the search query and your app name, subtitle, keyword field and primary category.
- User behavior: downloads, ratings and reviews, and other signals Apple doesn't list in detail.
A few practical consequences follow from this:
- If a word isn't in an indexed field, you are unlikely to rank for it. Writing "white noise" in your description is not the same as having it in your subtitle or keyword field.
- Relevance gets you into the race; behavior decides the order. A brand-new app can match a popular term perfectly and still sit far down the list behind apps with years of downloads and ratings.
- Apple adds context on top. Search results can show tags generated from your metadata, In-App Event cards, promoted in-app purchases and, if you set them up, custom product pages assigned to specific keywords.
The metadata fields you control
Everything you write for the App Store lives in App Store Connect. Some fields feed search directly; others exist only to persuade. Here is how they compare, based on Apple's App information and platform version references.
| Field | Limit | Used for search? | Change without a new version? |
|---|---|---|---|
| App name | 30 characters | Yes | No |
| Subtitle | 30 characters | Yes | No |
| Keyword field | 100 bytes | Yes (hidden from users) | No |
| Primary / secondary category | picked from a list | Yes | No |
| Promotional text | 170 characters | No, per Apple | Yes |
| Description | 4,000 characters | Not listed by Apple | No |
| What's New | 4,000 characters | No | With each version |
| Screenshots | up to 10 per size | No (conversion) | No |
| App previews | up to 3, 15–30 s | No (conversion) | No |
The three highlighted rows are where discovery happens, and together they give you only about 160 characters to describe your app to the search engine. That scarcity is why every word matters. Two dedicated guides go deeper:
- How to write an App Store title and subtitle that rank and convert.
- How to use the 100-character keyword field without wasting a byte.
Conversion: what makes people tap Get
Ranking puts you in front of people. Conversion decides whether they download. In search results, most of your listing is visual: the icon, the name and subtitle, the star rating and the first screenshots or preview video. Many people decide right there, without opening your product page.
Pages that convert
- Lead with the main benefit in the first two or three screenshots
- Use short, large captions that read at thumbnail size
- Show the real app in use, as guideline 2.3.3 requires
- Keep the icon simple and distinct from the top competitors
- Use the subtitle to say what the app does, in plain words
Pages that leak downloads
- A splash screen or login page as the first screenshot
- Tiny captions or feature lists nobody can read in search
- An icon that looks like the category leader's
- A subtitle that is a slogan with no information
- Few or no ratings, or old complaints left unanswered
Here's how two listings for the same kind of app can look side by side in search. Same category, very different first impression:
Ratings and reviews
Ratings do double duty. Apple says ratings and reviews can influence search ranking, and the star average and count sit right in the search result, where they shape the decision to download.
Three habits make the biggest difference:
- Ask at the right moment, with the system promptUse StoreKit's review request (
AppStore.requestReview(in:), orrequestReviewin SwiftUI) after a moment of success, not at launch. The system shows the prompt at most three times per 365 days per user, so don't waste it on a first session. - Reply to reviewsYou can respond to reviews in App Store Connect. A calm, helpful reply to a complaint is read by every future visitor who scrolls to it.
- Never buy or force ratingsApps must not force people to rate the app to unlock features (guideline 3.2.2), and manipulated or incentivized reviews can lead to removal from the Apple Developer Program.
When you ship a version that fixes a big problem, App Store Connect lets you reset the overview rating on release. Use it sparingly: it can't be undone, and Apple notes that having few ratings may discourage downloads. Written reviews stay visible either way.
Screenshots and app previews
You can upload up to 10 screenshots per device size and localization, and up to three app preview videos of 15 to 30 seconds each (Apple, app preview specifications). Only the first few are visible in search results, so treat them like a billboard, not a manual.
- Screenshot 1 states the core promise ("Fall asleep in minutes").
- Screenshots 2–3 prove it with the features people care about most.
- The rest handle objections: privacy, offline use, widgets, pricing model, awards.
Required sizes change as Apple ships new devices, so check the current list before you design. Our screenshot size guide keeps them in one place, and the upcoming screenshot guide covers design in depth.
Paste any App Store link and get a free ASO score with concrete fixes for the title, subtitle, screenshots and ratings.
Localization: the most underused lever
Apple's localization page describes the App Store as available in 175 regions and 50 languages. Every language you add gives you a fresh name, subtitle and keyword field to work with, and a product page that speaks to people in their own words.
Localization is not translation. Search terms differ from country to country, and a literal translation of your English keywords often misses what people actually type. Research each market's terms, then write metadata for them. Remember the keyword field is measured in bytes, so languages with non-Latin scripts fit fewer characters into the same 100 bytes.
The App Store localization guide covers how to choose markets and adapt screenshots.
Measuring ASO
You can't improve what you don't measure. App Store Connect's App Analytics gives you the core numbers for free:
| Metric | What it tells you | Which half of ASO |
|---|---|---|
| Impressions (from App Store Search) | How often your app was seen in search results | Discovery |
| Product page views | How many people opened your page | Discovery |
| Conversion rate | Share of visitors who downloaded | Conversion |
| Downloads by source | Search vs browse vs web referrer vs app referrer | Both |
| Ratings over time | Whether recent versions please users | Both |
Track your position for your most important search terms each week, and log every metadata change with its date. Without a change log, you'll never know which edit moved the numbers.
For visual assets you can run real experiments. Product Page Optimization lets you test up to three alternate versions of your icon, screenshots and preview videos against your original page, for up to 90 days. Text fields like the name and subtitle can't be A/B tested this way, so change them one at a time and compare periods.
A 30-day ASO plan
Here's a realistic month for a solo developer or small team. It assumes an app that's already live; if you haven't launched yet, use the ASO launch checklist instead.
- Days 1–3: Record a baselineExport impressions, product page views, conversion rate and downloads by source for the last 30 days. Write down where you rank today for 10–20 terms that describe your app.
- Days 4–7: Study competitors and build a keyword listSearch your main terms and note who ranks in the top results. Collect the words they use in names and subtitles. For each candidate keyword, weigh relevance to your app, search volume, and how strong the apps already ranking are.
- Days 8–12: Rewrite name, subtitle and keyword fieldPut your most valuable phrase in the name, your second tier in the subtitle and everything else in the keyword field, with no repeats. Submit a new version.
- Days 13–20: Fix the first three screenshotsRewrite captions around benefits, make them readable at thumbnail size, and start a Product Page Optimization test if you have enough traffic.
- Days 15–20: Tune your review promptMove the prompt to a moment of success and reply to the most recent critical reviews.
- Days 21–30: Measure and decideCompare rankings and conversion with your baseline. Keep what worked, revert what didn't, and pick one new localization or keyword cluster for next month.
ASO compounds. One good month won't transform an app, but twelve months of small, measured improvements usually will. Start with the fields that carry the most weight: your title and subtitle.
Frequently asked questions
How long does ASO take to show results?
Metadata changes only take effect once a new version is approved and live, and rankings then need time to settle. Plan to judge a change over a few weeks of App Analytics data rather than a few days.
Does the app description affect App Store search ranking?
Apple's search guidance lists the app name, subtitle, keywords and category as the text used for relevance, not the description. Write the description for people who are deciding whether to download.
Is ASO a one-time task?
No. Competitors, search trends and your own app change over time, so treat ASO as a loop: research, update metadata with each release, measure in App Analytics and repeat.
Can a tool guarantee a top ranking?
No. Apple decides rankings using relevance and user behavior that nobody outside Apple controls. Good tools help you choose better keywords and build a stronger product page, which improves your odds.
