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App Store Optimization (ASO)
28 Nisan 2021

Author: Engin YILDIZ, SW Architect – Web & Mobile Application Group;

What is App Store Optimization (ASO)

App Store Optimization on the basis means increasing organic downloads and improving app visibility within the app stores. The optimization is basically done by changing the app’s metadata like app name, title, icons, descriptions and screenshots. These metadata differ from each other in many ways, however, the ultimate goal remains the same.

ASO aims to increase the conversion of app impressions into downloads by using the method called conversion rate optimization, or click-through rate (CTR). It is done by convincing people to click the target app while searching or browsing. Statistically, in order to find an app around 70% of the visitors use search in stores and 40% of the apps are discovered through this process. ASO directly influences the resulting list of these organic searches.

Differences Between Stores

App Store and Google Play Store have a number of similarities. They both use complex algorithms and operate similarly for search results shown to the visitors. However, each of the stores has their own system and some parts of the metadata are evaluated differently.

Ranking factors are divided into on-metadata and off-metadata ranking factors. ASO in overall is considered as the sum of these factors. On-metadata factors could be modified by the publishers at all times. On the other hand, off-metadata factors are external factors and not under the control of the publisher. Some of the off-metadata factors are not known and remain hidden for the publishers.

On-Metadata Ranking factors

App name, app description, keywords, app url, in-app purchases and app visual assets

Off-Metadata Ranking factors

The number of installs, reviews, ratings, app updates and hidden factors

One key difference between the stores is Google Play Store keyword indexing works similar to Google Search engine which means Google takes all the textual metadata into account for keyword indexing. App Stores only uses app name, subtitle and keywords for textual ranking. Another key difference is keywords used for Google Play Store need repetitions at least more than twice in textual fields whereas App Store has a specific keyword field and does not need repetition.

How to Optimize Apps for Stores

App Name

App name is one of the elements of the app that primarily catches visitors’ attention. All the keywords used in app names (and app subtitles for App Store) are processed for keyword indexing. However, there are some limitations in terms of maximum characters allowed for app names. In the App Store, app name and app title have 30 and Google Play Store has 50 character limit.

When choosing the app name for both stores, it is advised to use the technique of “Brand Name: Main Features as Keywords”. The keywords extracted from the app name will be used in keyword indexing. Combinations of the keywords are also indexed when visitors are browsing.

Different from the Google Play Store, the App Store apps also have subtitles. App Store app names and subtitles together correspond to Google Play Store app names. It should be noted that the keywords coming after the brand names (or in subtitles for the App Store) must make a sensible sentence for both the stores. Putting only feature keywords after brand names could cause app rejection during the review process.

App Description

App description plays a key role in ranking algorithms and provides visitors with the information about the app and it’s features. Both the stores have 4000 character limits for app description and there are some differences between them.

The first difference is the App Store does not index keywords from app descriptions. This is the main reason why the app descriptions in the App Store are usually shorter than the ones in Google Play Store. In addition, as it was stated previously keyword repetition of keywords under the app description is also crucial for Google Play Store. Emojis in descriptions are also indexed in Google Play Store.

The second difference is the App Store provides a “Promotional Text” field and Google Play Store provides a “Short Description” field as a similar. App Store’s “Promotional Text” has 170 character limit and again is not indexed for keywords. It’s only usage is to give a brief idea about the app’s features without needing to read the full description. On the other hand, “Short Description” for Google Play Store has 80 character limit and keywords are again indexed.

Keywords (App Store Only)

Since the keywords from app description and promotional text in the App Store are not indexed for keywords, a separate keyword field is used for that purpose. This field is one of the most significant parts of the textual metadata. This is where all the features of the app could be turned into words and written down as keywords with a 100 character limit. When a visitor makes a search, all the keywords are either derived from this field or the app name and the keywords could also be combined.


Bundle identifiers for iOS apps and package names for Android apps are indexed for keywords. App URL could be made longer and added a few more keywords separated by dot.

In-App Purchases (IAP)

In-app purchases are considered as separate products. They have their own names, product identifiers and descriptions. All the textual metadata (except the descriptions in the App Store) for these products are also indexed for search algorithms. An IAP product can also be individually searched in the stores.

App Visual Assets

Apart from the textual on-metadata elements, there are some visual metadata assets that could be optimized for better results in the stores. Visitors usually spend at most 7 seconds to decide whether to download the app or not. Therefore, the more high-quality and proper assets the app has, the more chance the conversion rates will increase.

App Icons

App icons are the most effective part of the on-metadata elements. When visitors browse through the stores, app icons are the first elements that will catch their attention. It has a very robust effect on conversion rates. The key points to create a successful app icon is to make it catchy, simple, recognizable, unique and without texts on it. It is recommended to work the same icon on different backgrounds and apply A/B tests on a sample user group to pick the best performing one.

App Screenshots

App screenshots have also a profound impact on conversion rates. Both the stores have 10 screenshot limits yet all could be seen only if the app detail is clicked. Depending on the store and device, only up to 3 screenshots could be seen in the main search list. Therefore, the first 3 screenshots should be chosen among the most attractive ones. Furthermore, the file names of the screenshots in Google Play Store also contribute to the keyword indexing.

A common way to prepare screenshots is to take an in-app screenshot for the most privileged screens and depending on the design add a short description on the top/bottom of the screenshot. It is quite up to designers to decide on how to present the app in the stores, which is why there is no definitive way of doing it.

App Preview

App preview is a video preview of the app and located before the first screenshot. It is an optional on-metadata element and available for both the stores. It could be up to 30 seconds long and automatically played in mute when browsing so that it has to be pretty compelling at first glance.

The key for a successful app preview is showing a real experience of the app about what visitors could expect and want to know about it. The first 5 seconds should be really attractive since visitors usually spend around 3 to 5 seconds to watch an app preview.

App Localization

In order to get organic downloads worldwide the app should be localized in most of the available languages in the stores. All the on-metadata elements could be localized and it should be noted that localizing metadata does not affect the language support across the app. For instance, the app could only be in English and Turkish languages whereas its metadata could be in 20 different languages. This technique is usually applied to attract more users worldwide in the stores and it is always advised to support at least English language.


ASO Tools

There are some tools to be used when optimizing apps for the stores. Tools provides publishers with keyword suggestions according to region/language, screenshot/preview video quality feedback, app icon performance and so on. The features they provide are mostly paid services, however; offered free services are also useful to improve the quality of the app.

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