You know your app exists. Apple’s algorithm might not agree.
App Store optimization works against invisible signals. Apple doesn’t send a report card. You don’t get told that your description is too short, your screenshots aren’t filling the available slots, or that your app hasn’t been updated in eight months. You find out indirectly, when your ranking slides and you don’t know why.
We built the Marteso ASO Score Checker to make the invisible visible. Paste any iOS app URL and get a score from 0 to 100 based on 11 factors pulled from live App Store data. No account required.
Here is how the scoring works.
Why 11 factors
ASO is a combination of discoverability signals (can Apple index your app for the right queries?) and conversion signals (when users see your listing, do they download?). Both matter. An app that ranks but doesn’t convert is half-working. An app that converts beautifully but doesn’t rank gets no chances to prove it.
The 11 factors span both categories. Each factor has a defined point value and the total adds to 100. A locked bonus factor, Subtitle Optimization, is available to Marteso users and adds 15 more points to the full score.
Factor 1: Title Length (15 points)
Apple allows 30 characters in the app title. Every character you leave unused is discoverability you’re giving up.
The title carries the highest keyword ranking weight of any metadata field. Short titles leave keyword slots on the table. A title like “Focus” wastes 25 characters that could be used for ranked terms like “Focus: Deep Work Timer App.”
We score 15 points for titles 25 characters or longer, stepping down to 10 for titles 15 characters or more, and lower for shorter titles. If you score below 10 here, extending your title with primary keyword context is the first action.
Factor 2: Description Length (15 points)
The App Store description holds up to 4,000 characters. It is not a direct keyword ranking field the way your title is, but a structured, keyword-rich description improves conversion and signals to Apple that your listing is complete.
We score based on character usage: 15 points for descriptions at 3,000 or more characters, stepping down to 1 point for descriptions under 500. If you’re scoring low here, your description is probably one short paragraph when it should be a structured overview of use cases, key features, and the specific problems your app solves.
Factor 3: Rating (15 points)
Apps with average ratings below 4.0 are penalized in browse visibility. Apple’s algorithm factors ratings into how apps surface in curated sections and editorial placements, independent of keyword ranking.
We score full points for ratings 4.5 and above, stepping down to 2 points for ratings below 3.0. If you’re scoring low here, the fix is rarely the rating prompt. It’s identifying what users are disappointed about and addressing it at the product level first.
Factor 4: Rating Count (10 points)
A 4.8 rating from 3 users means something different than a 4.6 from 10,000. Apple weights both, but users making download decisions weight them very differently.
We score 10 points for apps with 10,000 or more ratings, stepping down to 1 point for apps with fewer than 10. The lever here is SKStoreReviewRequest, Apple’s native review prompt. Time it after a user completes a meaningful task or reaches a streak milestone, not at app launch when they haven’t seen enough of the product to rate it honestly.
Factor 5: Screenshots (10 points)
Apple provides 10 screenshot slots for iPhone. Most indie apps use 3 or 4.
Each unused slot is a missed conversion opportunity. The screenshot carousel is often the first visual content users engage with before scrolling down to read anything. We score 10 points for 8 or more screenshots, down to 1 point for 2 or fewer. If you’re at 3 or 4 screenshots, your action is clear: fill the remaining slots with screens that answer user objections or show features your first screenshots don’t cover.
Factor 6: Update Recency (10 points)
Apps that update regularly get re-indexed by Apple’s crawlers after each release. This resets the indexing clock for your keyword fields and can trigger ranking refreshes on terms where your position has been stale.
We score 10 points for apps updated within 30 days, declining to 0 points for apps with no update in over a year. If you’re scoring 0 or 3 here, a minor update shipping bug fixes and quality improvements can restart the indexing cycle without requiring new features.
Factor 7: Preview Video (5 points)
Apps with preview videos convert better than apps without them. The video reduces the uncertainty users feel about what the app does before they commit to a download, which is the core friction between seeing your listing and tapping Get.
We score 5 points for apps with a preview video, 0 for apps without one. The video doesn’t need to be produced with motion graphics. A 15 to 30 second screen recording showing your core flow captures most of the conversion benefit.
Factor 8: Localization (5 points)
Each localized App Store listing in a separate language and storefront is a separate discoverability surface. An app localized for German, French, and Japanese doesn’t just reach speakers of those languages. It gets indexed for keywords in those languages across those storefronts, expanding your keyword footprint without touching your primary listing.
We score based on the number of language localizations: 5 points for 6 or more languages, declining to 1 point for English-only listings. Even a single additional localization in a high-value market expands your organic reach in a way that keyword field optimization cannot.
Factor 9: iPad Support (5 points)
Universal apps with iPad screenshots in their listing access a larger audience and are eligible for editorial featuring in iPad-specific sections Apple curates independently of iPhone charts.
We score 5 points for apps with iPad screenshots, 2 points for iPhone-only apps. If your app already runs on iPad but you haven’t added iPad screenshots to your listing, you’re cutting off discoverability in a segment you’ve already built for.
Factor 10: Monetization (5 points)
Apps with a clear monetization model, paid upfront or free with in-app purchases, signal quality and completion to users. Free apps with no visible monetization often read as either abandoned or ad-supported without disclosure, both of which increase the mental friction before a download.
We score 5 points for paid apps or apps with in-app purchases, 3 points for free apps without IAP. If you’ve built a sustainable product without a visible purchase flow, this is worth addressing on ASO grounds independent of the revenue consideration.
Factor 11: App Size (5 points)
Smaller apps download faster and see better conversion on slow connections. A download that completes in seconds is part of the first impression. On cellular, an app showing a 2.3 GB download creates friction that a 45 MB app doesn’t create.
We score 5 points for apps under 50 MB, stepping down to 2 points for apps over 200 MB. If your app is large because of bundled assets, on-demand resources and asset streaming can bring the initial download size down without removing features.
Reading your results
A score below 60 typically points to 3 or 4 specific factors dragging the total down. Focus on the factors with the largest gap between your score and the maximum. Title Length, Description Length, and Screenshots are the fastest to fix and carry the most combined weight in the scoring model.
A score between 60 and 80 means your basics are covered. The next improvements come from higher-effort factors: adding a preview video, expanding localization coverage, and maintaining a consistent update cadence.
A score above 80 means you’re optimizing at the margins. The biggest unlock at this level is usually the Subtitle Optimization factor, which requires tracking keyword performance over time to make the right placement decisions. That factor is part of Marteso’s full analysis.
Try it on your app
The ASO Score Checker is free and requires no account. Paste your App Store URL and get your score in seconds. The factor breakdown shows you exactly where you’re losing points and what to fix first.