iOS App Store Optimization (ASO) Guide

ASO drives ~40% of app discovery. Get this right and you have a free, compounding growth channel.

How App Store Search Works

Apple indexes these fields for search:

NOT indexed: Full description, "What's New" text, review content. (Unlike Google Play, Apple does NOT search the description.)

Keyword Research Process

Step 1: Brainstorm Seed Keywords

Start with 20-30 keywords a user might search:

• Core function ("habit tracker", "sleep sounds")
• Problem being solved ("can't sleep", "track spending")
• Category terms ("productivity app", "fitness tracker")
• Competitor names (yes, you can rank for these)
• Synonyms and variations ("journal" vs "diary" vs "log")

Step 2: Evaluate Keywords

For each keyword, assess:

• Relevance: Does it describe what your app does? (Must be high)
• Search volume: Are people actually searching this? (Check autocomplete in App Store search — if it autocompletes, it has volume)
• Competition: How many strong apps rank for this? (Search it and see)
• Difficulty: Can you realistically rank on page 1?

Step 3: Prioritize by Opportunity

Step 4: Optimize the Keyword Field

The 100-character keyword field is your most underutilized asset:

Rules:

• Comma-separated, no spaces after commas
• Do NOT repeat words already in your app name or subtitle
• Do NOT use "app", "free", or category names Apple adds automatically
• Use singular OR plural, not both (Apple matches both)
• Include common misspellings of competitor names
• Use the full 100 characters — every character counts
• Separate word fragments get combined by Apple's algorithm

Example: App name: "ZenSleep - Sleep Sounds" Subtitle: "White Noise & Relaxation"

Keyword field (100 chars):

insomnia,meditation,calm,rain,ocean,fan,nature,bedtime,nap,rest,snore,baby,asmr,anxiety,stress,focus

Notice: no "sleep", "sounds", "white", "noise", or "relaxation" — those are already in the name/subtitle.

Screenshot Strategy

Screenshots are the #1 conversion factor after the app name/icon.

Best Practices

1. First screenshot is critical — it's the only one most people see in search results
2. Show the app in use, not just UI — demonstrate the value proposition
3. Add captions — short, benefit-focused text above/below the screenshot
4. Use all 10 slots — more screenshots = more real estate in search results
5. Design for 6.7" (iPhone Pro Max) — this is the required size, others are generated automatically

Screenshot Sequence Formula

App Preview Video

• Length: 15-30 seconds (shorter is better — most people won't watch 30s)
• Format: Show the app being used, not a cinematic trailer
• First 3 seconds: Must hook — show the core value immediately
• No text-only frames — Apple may reject
• Autoplay: Videos autoplay on mute in search results — make it visually compelling without audio

Subtitle Optimization

The subtitle is prime real estate — 30 characters that appear in search results.

Good subtitles:

• "Smart Habit Tracker & Streaks" (keyword-rich, benefit-clear)
• "Block Ads & Trackers Everywhere" (action + scope)
• "Budget Planner & Bill Tracker" (two keywords)

Bad subtitles:

• "The Best App Ever" (no keywords, no value)
• "Version 2.0" (wasted space)
• "By [Company Name]" (no value to user)

App Name Strategy

Your app name has 30 characters. Use them wisely:

Formula: {Brand Name} - {Primary Keyword Phrase}

Examples:

• "Sentinel - Ad Blocker & Privacy" (brand + category + differentiator)
• "PennyPal - Budget with Your Pet" (brand + category + hook)
• "CozyFarm - Garden Sim Game" (brand + category)

Rules:

• Brand name first for memorability
• Dash separator is standard
• Include your #1 keyword phrase after the dash
• Don't stuff keywords — Apple rejects "spammy" names

Localization for ASO

Localizing your App Store listing (even without translating the app itself) gives you access to keyword rankings in other languages:

High-value localizations for US developers:

• Spanish (US has 40M+ Spanish speakers)
• French (Canadian market)
• Portuguese (Brazilian market)
• German (high-spending European market)
• Japanese (high ARPU, premium market)

You can localize just the metadata (name, subtitle, keywords, screenshots) without localizing the app itself.

ASO Iteration Cycle

ASO is not set-and-forget. Iterate monthly:

1. Track rankings for your target keywords (use App Store Connect or free tools)
2. Monitor conversion rate in App Store Connect analytics
3. A/B test screenshots and descriptions (available via App Store Connect product page optimization)
4. Update keywords based on what's working and trending
5. Respond to reviews — Apple considers developer engagement
6. Update regularly — apps updated recently rank higher than stale ones