When most indie devs optimize their App Store listing, they obsess over the title and keyword field. That makes sense — they're the two heaviest-weighted fields in Apple's search algorithm. But there's a third field sitting right between them in importance, and almost nobody treats it with the respect it deserves: the subtitle.

Apple gives you 30 characters for your subtitle. That's roughly five words. Used well, they can be the difference between ranking #38 and ranking #12 for a keyword that matters. Used poorly — or worse, left as an empty afterthought — they're free real estate you're handing to your competitors.

Let's break down exactly how the subtitle works, what Apple does with it, and how to write one that pulls its weight.

What the subtitle actually does

The subtitle sits directly below your app name on the product page. Visually, it's the second thing potential users see. Algorithmically, it's indexed for search — meaning every word you put there can help your app surface for relevant queries.

Here's what surprised me when I started digging into ranking data: the subtitle carries more weight than the keyword field for exact-match searches.

I saw this play out with a meditation app I was tracking. Its title was "Calm Space — Meditation & Sleep," its subtitle was "Relax, focus, breathe," and its keyword field was packed with terms like "mindfulness," "stress relief," and "anxiety help." Despite "mindfulness" being in the keyword field and nowhere in the subtitle, the app ranked #42 for "mindfulness" and #17 for "breathe" — a word that only appeared in the subtitle.

The pattern holds across categories. Apple's algorithm appears to treat the subtitle as an extension of the title rather than a separate metadata bucket. That means substring matches in the subtitle get a relevance boost that keyword-field matches don't.

The subtitle vs. the keyword field

This is where most developers get confused. If the subtitle is indexed, why not just stuff keywords in there and call it a day?

Two reasons:

1. Users read it. Unlike the keyword field (which is invisible to users), people actually scan subtitles when browsing search results. A subtitle that reads "Meditation, sleep, relax, focus" looks like keyword spam and tanks your conversion rate. You're trading a small ranking gain for a larger conversion loss — a bad deal.

2. Apple reviews subtitles. Apple's review guidelines explicitly call out the subtitle: it must be a "brief summary of your app," not a keyword list. Apps that stuff keywords into the subtitle risk rejection or, worse, having their subtitle changed during an update when they're not paying attention.

The art of subtitle optimization is threading the needle: include high-value keywords in a way that reads naturally as a description of what your app does.

The 5 rules of a high-performing subtitle

After analyzing subtitles across hundreds of apps and correlating them with ranking data, here's what consistently works:

Rule 1: Don't repeat words from your title

Apple doesn't double-count keywords. If your title is "Focus Keeper — Pomodoro Timer," putting "Pomodoro Timer" in your subtitle gives you exactly zero additional ranking benefit for those words. It's wasted characters.

Instead, use the subtitle to cover adjacent search terms. For Focus Keeper, a subtitle like "Deep Work & Study Sessions" captures "deep work" and "study" — terms the title misses entirely.

Rule 2: Lead with your highest-value uncovered keyword

The first 2-3 words of your subtitle carry the most weight. Identify the highest-traffic keyword you're not already covering in your title, and put it first.

For a habit tracker titled "Streaks — Daily Habit Tracker," the subtitle might be "Routine Builder & Goals." "Routine" and "goals" are both high-volume search terms in the productivity category that the title doesn't touch.

Rule 3: Write for humans, optimize for algorithms

A good subtitle should answer "what does this app actually do?" in a single breath. If it passes the "would I say this to a friend?" test, you're on the right track.

Bad: "Workout fitness gym exercise plan" Good: "Home Workouts & Fitness Plans"

The second one reads like a subtitle. The first reads like a spreadsheet. Both contain keywords — only one converts.

Rule 4: Don't waste characters on your brand name

I see this constantly: "Photo Editor by CoolAppCo" or "CoolAppCo Filters & Effects." Unless your brand is a search term people actually type, don't put it in the subtitle. Those precious characters should go toward keywords that drive discovery.

Your brand is already in your app name and your developer name. It doesn't need a third mention.

Rule 5: Test, don't guess

The subtitle isn't set in stone. You can change it with every app update — and you should, at least until you find what works. The problem is that most developers change their subtitle on a hunch and never measure the result.

What to measure:

  • Keyword ranking movement for the terms you added or removed
  • Impression-to-page-view conversion (are more people tapping through from search results?)
  • Download rate (are the people who land on your page actually installing?)

If you add a keyword to the subtitle and see a ranking jump from #45 to #20 within two weeks — that's the signal. If nothing moves, try a different approach next update.

Real example: A subtitle turnaround

A scanner app I tracked was ranking around #30-40 for most of its target keywords. Its title was "ScanPro — PDF Document Scanner" and its subtitle was "Scan, sign, and share docs."

The problem? The subtitle was wasting words. "Scan" already appeared in the title. "Docs" was covered by "Document." And "share" is rarely a discovery keyword for scanner apps.

After the developer updated the subtitle to "OCR Text Recognition & Fax," here's what happened in three weeks:

| Keyword | Before | After | Movement | |---------|--------|-------|----------| | OCR | Not ranked | #14 | New ranking | | Text recognition | #58 | #23 | +35 positions | | Fax | Not ranked | #8 | New ranking | | Scan documents | #31 | #28 | +3 positions |

The "scan documents" ranking barely moved — because the title already covered it. But "OCR" and "fax" opened up entirely new discovery channels. That's what a good subtitle does: it expands your keyword footprint without cannibalizing what you already have.

Common subtitle mistakes to avoid

The empty subtitle. Some developers literally leave this blank. If you do nothing else today, put something there.

The feature list. "AI, PDF, edit, crop, filter, resize" — Apple may reject this, users definitely ignore it, and it doesn't even rank well because there's no semantic coherence.

The tagline that says nothing. "Make every day amazing" is a nice sentiment. It also contains zero keywords anyone searches for. Save the poetry for your description.

The localization fail. If you've localized your app for other markets but left the subtitle in English, you're leaving rankings on the table. Localize your subtitle too — the character limit is tight, but the ranking impact in non-English markets is real.

How to find your best subtitle keywords

Start with your existing keyword data. Which terms do you rank #20-50 for — close enough that a relevance boost could push you into the top 10? Those are your subtitle candidates.

Next, look at competitor subtitles. Not to copy them (please don't), but to spot keywords they're missing. If three meditation apps all have subtitles about "relaxation and sleep," the term "mindfulness meditation" might be an open lane.

Finally, use App Store autocomplete to find what people are actually searching for. Type your category into the App Store search bar and note the suggestions. Those are real queries from real users. If "workout planner for women" auto-completes, and your app serves that audience, work "Workout Planner" into your subtitle.

The bottom line

Thirty characters isn't much. But used strategically, your subtitle can open keywords your title doesn't cover, improve your search result conversion rate, and do it all in a field Apple clearly weights above the keyword bank.

If you're not thinking about your subtitle as a ranking tool, you're not doing ASO.

Want to see exactly how your subtitle changes affect your keyword rankings? aso.cristomade.it tracks your app's positions daily, so you can test subtitle changes and watch the impact in real time — no guesswork required.