App Store Optimisation (ASO)

As a significant proportion of all app downloads originate from the store’s internal search function, ASO is not an afterthought in marketing, but rather part of the launch process, which ideally begins before the launch and continues on an ongoing basis thereafter.

The term is sometimes narrowly misunderstood as purely keyword optimisation. In fact, ASO encompasses all work relating to the app’s store presence: from the choice of search terms and the design of the icon and screenshots to managing reviews and localisation for different markets. All these elements contribute to two measurable metrics: namely, how often an app appears in search results and how many visitors subsequently install it.

The two tasks of ASO: visibility and conversion

App Store Optimisation breaks down into two clearly distinct tasks, each involving different levers. Anyone who views ASO as merely a ‘keyword exercise’ is missing out on half its potential. The two tasks are interlinked, but can be managed and measured separately.

Visibility: the search terms for which the app appears

Visibility determines for which search queries the app appears in the results at all. It is controlled via the metadata fields that the store algorithm indexes. The fields given the highest weighting are the title (app name) and the subtitle. The title usually combines the brand name with one or two strong keywords, whilst the subtitle conveys the core benefit plus other relevant terms. If you only include the brand name here and leave the keyword fields unused, you’re missing out on potential reach. The algorithm also forms combinations from the individual words in the fields, so that ‘invoices’ and ‘accounting’ can also cover the phrase ‘invoices accounting’ without it having to be typed out verbatim.

A sensible keyword strategy starts with a core set of around 20 to 40 terms that the app should consistently target, supplemented by a longer test list of 100 or more terms for future versions. The trend is towards more specific long-tail queries: longer, more concrete search phrases which, whilst having lower search volume, are less competitive and drive more targeted traffic. A new app rarely ranks for competitive single terms right from the start anyway; by contrast, initial visibility can be built up more quickly using specific phrases.

Conversion: Encouraging visitors to the product page to install the app

The second task begins as soon as a user lands on the product page. Within a few seconds, the decision is made as to whether or not the app will be installed. Conversion is primarily driven by the app icon, the screenshots, the preview video and the reviews. The first two to three screenshots are particularly important because, on many search results pages, they appear directly below the title, even before a user opens the page. They should immediately highlight the core benefits, rather than starting a feature tour from the beginning. Reviews serve a dual purpose: as a sign of trust for the user and as a ranking factor for the store. A high conversion rate also indirectly boosts visibility, as a high number of installations from search results signal to the algorithm that the app is relevant to the query in question.

ASO in the Apple App Store and on Google Play

Both major app marketplaces pursue the same goal, but index metadata differently. Anyone managing both platforms must maintain the fields separately and cannot simply copy the text over one-to-one.

The most important practical difference: Apple offers a hidden 100-character keyword field that is not visible to users but counts towards search results. A frequently overlooked feature here is that Apple only counts each keyword once. Duplicating terms across the title, subtitle and keyword field therefore wastes valuable space. Google Play does not have such a field; instead, Google indexes the visible description text, which is why the relevant terms naturally belong in the short and long descriptions there. This single structural difference accounts for almost the entire difference in approach: with Apple, the limited keyword space is carefully curated; with Google, an easily readable yet keyword-conscious description is written.

An overview of the most important ASO levers

• Title and subtitle: the fields with the highest weighting. Brand name plus the strongest keywords.
• Keyword field (Apple) or description (Google): the place for the remaining relevant search terms.
• Icon: the first visual impression, often decisive for clicking from the results list.
• Screenshots and preview video: account for the majority of conversions; the first screenshots appear in the search results.
• Ratings and reviews: both a trust signal and a ranking factor.
• Localisation: metadata that has been translated and adapted to the market increases visibility and conversion in every target country.

Localisation as an underestimated lever

Both stores allow metadata to be specified per language and region. Anyone who maintains an app in German or English only is practically invisible in other markets, even if the app is technically multilingual. Localisation involves more than just translation: search terms that are common in one market may have hardly any search volume in another, and screenshots featuring localised text generally convert better too. Apple also offers so-called localisation slots, which can be used to expand the indexed keyword space, for example by maintaining an additional locale alongside the main language.

Example: the keyword field in the Apple App Store

A concrete example illustrates how this works. Let’s assume an accounting app is called “Rechnio”. The title field reads “Rechnio – Invoices & Accounting”, whilst the subtitle reads “Scan receipts, VAT, DATEV export”. The hidden 100-character keyword field in App Store Connect would then not contain “invoice” or “accounting” again, because these terms are already present in the title and subtitle and Apple only counts them once. Instead, supplementary terms such as “freelancer,small business owner,eur,gobd,tax adviser” are included there, separated by commas and without spaces to save characters. In this way, each field covers a different part of the relevant search space, rather than cannibalising itself. Apple describes how to maintain these fields in the official documentation for the App Store product page.

Common ASO mistakes

• Underestimating the title and subtitle: These fields carry the most weight. Filling them only with the brand name wastes the most important ranking signal.
• Duplicating keywords: In the Apple App Store, each word counts only once. Repeating the same terms in the title, subtitle and keyword field wastes space.
• Treating screenshots as a mandatory field: Uploading random app screenshots instead of tailoring the first few to highlight the app’s core benefits will result in lost conversions.
• Omitting localisation: A technically multilingual app without localised metadata remains invisible in foreign-language markets.
• Viewing ASO as a one-off setup: Without regular updates to keywords and assets, the listing becomes outdated and loses ground to actively maintained competitors.

Measuring ASO: how to gauge success

To ensure ASO isn’t left to gut feeling, both tasks can be tracked using specific metrics. For visibility, these are impressions (how often the app appears in search and browse results) and keyword rankings (the position the app holds for defined terms). For conversion, the most important metric is the conversion rate, i.e. the proportion of page visitors who actually install the app. Apple provides this data in App Store Connect via App Analytics, whilst Google provides it in the ‘Store Performance’ section of the Play Console. This allows changes to titles, subtitles or screenshots to be compared before and after an update. Apple also offers product page tests, which allow different icon or screenshot variants to be compared against one another before a variant is rolled out permanently. It is important to change only one variable at a time, as otherwise the effect cannot be clearly attributed.

ASO and SEO: related, but not identical

ASO and SEO share the basic idea of being found via relevant search terms, but differ in the details. In traditional SEO, search engines evaluate thousands of signals, including many external ones such as backlinks. In the App Store, the scope is narrower: What counts most are the platform’s own metadata, download and usage figures, and ratings. External factors play a lesser role. In contrast, the conversion component is more pronounced in ASO, as the decision to ‘install or not’ is made directly on the product page. Both disciplines benefit from thorough keyword research and from ensuring that the description accurately reflects the actual scope of functionality – not least because misleading metadata in the App Store is in itself a reason for rejection during the review process.

Frequently asked questions about App Store Optimisation (ASO)

Is ASO a one-off setup?
No. ASO is an ongoing process. Titles, subtitles, keywords and screenshots are refined with every app version; variants are tested and measured against performance. To get started, however, it is sufficient to carefully craft the title, subtitle and the first three screenshots.

How many keywords should an app target?
A practical starting point is a core set of 20 to 40 keywords that the app should consistently target, supplemented by a longer list for testing. The focus is increasingly on specific long-tail queries with less competition.

Which is more important, visibility or conversion?
The two are interlinked. Visibility brings visitors to the product page; conversion turns them into installations. A highly visible app with poor screenshots will lose the visitors it has attracted, whilst a perfectly designed page with no visibility will attract none.

Does ASO differ between Apple and Google?
Yes. Apple has a hidden 100-character keyword field and evaluates each keyword only once. Google Play has no such field and instead indexes the visible description text. The fields must be managed separately for both platforms.

When should ASO begin?
Ideally, before launch. Keyword research, titles, subtitles and screenshot concepts are all part of launch preparations, as they determine visibility from day one. After launch, ongoing optimisation begins based on real data.