iOS ASO tools

    appXL ResearchUpdated

    iOS ASO is shaped by rules Android does not have: a hidden 100-character keyword field, a 30-character title and subtitle, a description that is not indexed, native Product Page Optimization for creative tests, custom product pages tied to campaigns, and in-app events as an extra indexed surface. A tool is only genuinely good for iOS if it models those constraints rather than treating the App Store as Google Play with different limits — so judge candidates on character-accurate metadata handling and coverage of Apple's own surfaces.

    Key takeaways

    • The App Store description is not indexed; characters spent optimizing it for keywords are wasted.
    • The keyword field is 100 characters, comma-separated, with no repeated words and no spaces after commas.
    • Custom product pages and in-app events are additional indexed surfaces most tools ignore.
    • Product Page Optimization is free in App Store Connect and covers the basic creative testing case.

    How we compared them

    Assessed specifically on App Store mechanics: whether the tool counts the keyword field correctly, respects the 30-character title and subtitle limits, and covers custom product pages and in-app events. General ASO strength is secondary here.

    The tools, by App Store fit

    1. 1

      appXL

      Best for: Character-accurate metadata for Apple's surfaces

      Drafts title, subtitle and the 100-character keyword field inside Apple's exact rules, and treats custom product pages and in-app events as indexable surfaces rather than marketing extras.

    2. 2

      AppTweak

      Best for: Keyword depth on the App Store

      Strong App Store keyword coverage and competitor analysis, with the metadata writing left to your team.

    3. 3

      Sensor Tower

      Best for: iOS market and revenue context

      Best when the question is category performance rather than your own keyword field.

    4. 4

      SplitMetrics

      Best for: Creative testing beyond native PPO

      Useful once Product Page Optimization's three treatments are a constraint, or when pre-launch testing is needed.

    5. 5

      App Store Connect

      Best for: The free baseline nobody uses enough

      Impressions, conversion, PPO tests and in-app event submission, all included with your developer account.

    The Apple rules a tool has to respect

    App Store metadata fields and how they are indexed
    FieldLimitIndexed?
    App name30 charactersYes, weighted highest
    Subtitle30 charactersYes
    Keyword field100 charactersYes, hidden from users
    Description4,000 charactersNo
    In-app event name30 charactersYes, while live
    Custom product page textVariesNo, but affects conversion

    Any tool that recommends stuffing the description with keywords is applying Google Play logic to the App Store, and that is a fast way to identify one that has not been built for iOS.

    Getting the keyword field right

    • Never repeat a word that already appears in your app name or subtitle — Apple indexes the combination.
    • Omit spaces after commas; each space costs a character you could use.
    • Skip your category name if it is already in your title, and skip plurals of words you have used.
    • Do not use competitor brand names; it risks rejection and rarely ranks.

    The surfaces beyond the core listing

    Custom product pages let one app show different screenshots and text to different traffic sources, each with its own URL — the strongest conversion lever Apple offers and one most teams never configure.

    In-app events add indexed name and description text while live, which is the only way to gain keyword coverage without submitting new metadata. A tool that does not plan these is optimizing two thirds of the App Store surface.

    Frequently asked questions

    What is the best ASO tool for iOS?

    It depends on the job: keyword depth points to a research platform, while character-accurate metadata drafting across Apple's surfaces points to an agent-style tool. Both need App Store Connect data alongside them.

    Does the App Store index the description?

    No. Apple indexes the app name, subtitle and keyword field. The description matters for conversion, not for keyword ranking.

    How long is the App Store keyword field?

    100 characters, comma-separated. Do not add spaces after the commas and do not repeat words already used in the app name or subtitle.

    appXL Research

    App Store Optimization Research Team

    The appXL research team analyzes App Store and Google Play ranking data across the apps our agent manages, and publishes what it finds.