TL;DR

Most ASO guides are written for apps with 100k+ users and enterprise budgets. This one is for indie developers who need to find 15–25 keywords that can actually rank. It takes about 4 hours total.

What ASO keyword research really is

App Store keywords live in four places:

App name (30 chars) — highest weight
Subtitle (30 chars) — second highest
Keywords field (100 chars, comma-separated, not shown to users) — third
Description (4000 chars) — minimal ranking weight (mostly for indexing context)

Your goal is to find keywords that (a) users actually search for, (b) aren't dominated by Big Tech incumbents, and (c) describe your app accurately.

Step 1: Brainstorm seed keywords (30 min)

Write 20–30 candidate phrases. Mix:

Category terms: "budget app", "habit tracker", "recipe manager"
Outcome terms: "save money", "build habits", "lose weight"
Mechanic terms: "pomodoro timer", "offline translator", "sleep sounds"
Brand comparisons: "notion alternative", "habitica alternative"

Don't filter yet. Just brainstorm.

Step 2: Research search volume & difficulty (90 min)

You need a tool. Free/cheap options:

Sensor Tower — $0 trial, $79+/mo after
AppTweak — $0 trial, $79+/mo after
App Radar — has a free tier
Google Keyword Planner — free but web-focused, use as directional signal

For each seed keyword, record:

Search volume (SAP score or similar): higher = more users searching
Difficulty: higher = more competition

The goldilocks zone for indie apps: volume ≥ 20, difficulty ≤ 40. Too low volume and nobody searches; too high difficulty and you'll never rank.

Free alternative: search the exact phrase on the App Store and count how many results use the word in their title. If the top 10 all have it in the title — difficulty is high. If only 2–3 do — you have a shot.

Step 3: Spy on competitors (60 min)

Pick 5 apps similar to yours. For each:

Read their app name and subtitle. What keywords are they going after?
Check their ratings/reviews. Reviews often mention the search terms users use — goldmine.
Use a tool to extract their Sensor Tower keyword set if you have access.

You're looking for keywords a competitor has started ranking on but isn't obsessed with — signals it's reachable.

Step 4: Prioritize (30 min)

Now pick 3–5 primary keywords (to go in app name + subtitle) and 15–20 secondary keywords (for the 100-char keywords field).

Primary criteria:

Describes your core feature
Volume ≥ 40 (meaningful traffic)
Difficulty ≤ 50 (winnable)
You'd be comfortable if your app page showed this as the headline

Secondary criteria:

Long-tail variations ("budget tracker for couples", "offline habit tracker")
Brand comparisons
Seasonal terms if relevant

Step 5: Write the assets (60 min)

App name (30 chars): brand + 1 primary keyword. Example:

❌ "BudgetPro"
✅ "BudgetPro — Budget Tracker"

Subtitle (30 chars): 2–3 secondary keywords. Example:

❌ "Take control of your finances"
✅ "Save Money. Track Expenses."

Keywords field (100 chars, no spaces after commas): stuff 15–20 secondary keywords, each appearing only once.

✅ "finance,money,expense,bill,spending,save,income,debt,card,budget,tracker,ledger,wallet,cash"

Description: write for humans. Don't keyword-stuff. Put your strongest 3–5 keywords in the first 2 sentences. Apple's algorithm indexes the first ~500 chars most heavily.

Step 6: Ship and measure

Publish, then wait 2–3 weeks for keyword rankings to stabilize. Track per-keyword rankings weekly. Kill any keyword that's not ranking in the top 30 after a month, and replace it.

Common mistakes

Chasing head terms. "game", "photo", "chat" — you will never rank. Stick to long-tail.
Stuffing keywords. Apple's algorithm penalizes listings that feel spammy. Readable > dense.
Ignoring localization. Each locale has its own keywords field. See localization guide.
One-and-done. ASO is iterative. Re-run keyword research every 3 months.

Tools stack (free-ish)

Seed brainstorming: Google Docs
Search volume directional: Google Keyword Planner (free)
Difficulty signal: manual App Store search + count
Rank tracking: App Radar free tier, or App Store Connect impressions reports
Screenshot generation: ScreenFast ($9.99)

ASO Keyword Research for Indie Developers: The Practical Guide