How do you optimize an App Store listing for a technical app?
App Store optimization is the work of choosing words and visuals so the right professionals find your app and install it. For a technical app the words are unusually specific: units, standards, component names and job titles. This guide covers the fields Apple indexes, their limits, how to research terms and a full rewrite of a fictional engineering calculator.
What is App Store optimization for a technical app?
ASO means choosing the app name, subtitle, keywords, category and visuals so your app appears for the searches your users make and earns the tap and the download. Apple states that text relevance comes from the name, subtitle, keyword field and primary category, while downloads, ratings and reviews also influence results; see Search on the App Store.
For an engineering or field app the work is narrower than for a consumer app. Search volume is small, but each search is precise: "flange bolt torque", "thread pitch chart", "preload calculator". Ranking for twenty precise phrases is worth more than chasing one broad term like "calculator".
Calculate anything, faster.
Metric and imperial bolts, lubrication factors and thread pitch tables, with every result saved to a job so you can show your working.
Which App Store fields affect search, and what are their limits?
Know the limits before you write, because every character in the indexed fields is scarce. The figures below come from App Store Connect app information and platform version information.
| Field | Limit | Indexed for search? | Use it for |
|---|---|---|---|
| App name | 2 to 30 characters | Yes | Brand plus main task |
| Subtitle | Up to 30 characters | Yes | Result or audience |
| Keyword field | Up to 100 bytes; commas, no spaces | Yes | Long-tail task terms |
| Primary category | One choice | Yes | Where your users browse |
| Promotional text | Up to 170 characters | No | Timely news for visitors |
| Description | Up to 4,000 characters | No | Detail for evaluators and buyers |
Note the keyword field is measured in bytes. Plain English letters take one byte each, but accented characters and some symbols take more, so a French-Canadian localization can fit fewer terms than you expect.
How do you research keywords for an engineering or field app?
Start from tasks, not from a keyword tool. Tools estimate popularity poorly for small professional niches. Interview users, read support tickets and look at the words in standards and spec sheets your users work from. Then group the terms.
Task terms
What the user is trying to do.
Components and standards
Nouns from drawings and specs.
Job titles
Useful when the task is broad.
Avoid
Wrong intent or not allowed.
Then write the keyword field: lowercase, commas, no spaces, no plurals of words you already have unless users clearly search both forms. A draft for the fictional Torque Calc Pro reads preload,fastener,flange,clamp,thread,pitch,metric,imperial,millwright,lube,spanner,wrench,nm, which uses 92 of the 100 characters. "Torque", "bolt" and "calc" are left out because the name and subtitle already carry them.
What is the order of work for an ASO pass?
- List 30 to 50 candidate phrases from interviews, tickets and spec sheets.
- Search each one on a phone and note who ranks and whether results match the task.
- Pick the main task for the name and the result for the subtitle. Read them aloud as one line.
- Fill the keyword field with remaining single words that combine into your phrases.
- Choose the primary category where competitors with the same task appear.
- Rewrite the first three screenshots so each one names a task from your list. See screenshots and previews.
- Ship with a version, wait for results to settle, then compare impressions and conversion by search term.
- Repeat every quarter, swapping weak terms for new ones.
If you also publish on Android, run the same research for Google Play, where there is no keyword field and the rules on wording differ. ShoutEx view: treat the full description as text Play can match.
One field, one job.
The name carries the brand and the main task, the subtitle carries the result, the keyword field carries the long tail. Never spend characters repeating a word that already sits in a field Apple reads.
What does a full listing rewrite look like?
| Field | Before | After | Why |
|---|---|---|---|
| Name | TorqueCalc | Torque Calc Pro | Brand stays; words read naturally |
| Subtitle | The smart calculator app | Bolt torque and preload calcs | Two task terms instead of filler |
| Keywords | calculator,app,smart,tool,best | preload,fastener,flange,clamp,thread... | Long tail; no repeats or claims |
| Category | Utilities | Utilities (checked against competitors) | Kept after a search check |
| Screenshot 1 | Welcome to TorqueCalc | Torque from bolt size and grade | Shows the result in search |
| Promo text | Calculate anything, faster. | Metric and imperial bolts, lube factors... | Answers "will it handle my units?" |
What ASO mistakes are common with technical apps?
- Using marketing adjectives (smart, powerful, ultimate) in the subtitle instead of task words.
- Stuffing the name with five terms so it no longer reads as a product name.
- Repeating words across name, subtitle and keyword field, which wastes characters.
- Ignoring units and standards. An engineer searching "metric" or a standard's number is very close to installing.
- Changing everything at once. When name, screenshots and keywords all change in one version, you cannot tell which helped.
- Never localizing. A French-language listing for Quebec users is a separate set of fields and terms.
Trade-off: specific words reduce total impressions. For apps that sell to professionals, a smaller audience that activates is cheaper to serve and easier to convert. The SaaS keyword research guide uses the same intent logic on the web.
How do you know if ASO changes worked?
| Metric | Question it answers | Where to find it |
|---|---|---|
| Search impressions | Are we shown for more of the right searches? | App Store Connect, source: Search |
| Search conversion rate | Do the new words and screenshots earn installs? | App Store Connect |
| Ranking for target terms | Where do we sit for each phrase? | Manual phone checks or an ASO tool |
| Activation by source | Do search users complete a first calculation? | Your product analytics |
| Paid conversion | Do they pay later? | App Store Connect proceeds, your billing |
Keep a simple change log with the date, the fields changed and the reason. After two or three cycles you will know which kinds of words move installs for your trade. Pair it with analytics and attribution so you can follow a search user to a paid account.
Frequently asked questions
How long can an App Store app name be?
Between 2 and 30 characters. The subtitle can also be up to 30 characters.
How long is the App Store keyword field?
Up to 100 bytes, written as words separated by commas with no spaces. Accented characters can take more than one byte.
Does the App Store description affect search?
Apple lists the name, subtitle, keyword field and category as the text it uses for relevance. Write the description for people who are deciding, not for search.
Should I put competitor names in my keywords?
No. It risks rejection and attracts people looking for another product.
How often should I change App Store keywords?
Review them every quarter and change a few at a time so you can see which change made a difference.
Is ASO worth it for a niche B2B app?
Yes, because niche searches are precise. Ranking for many small technical phrases often brings users who activate at a higher rate than broad traffic.
What is promotional text used for?
Promotional text, up to 170 characters, sits near the top of the product page. Use it for timely news; Apple does not list it among the fields used for search relevance.
Sources & further reading
Regulator rules, platform policies and local data change. These sources let you check the facts on this page, last checked October 6, 2026.