mobile app localization

The Ultimate Guide to Mobile App Localization

When you develop a mobile app, the goal is usually to achieve maximum traction. That means maximizing the number of users and the amount of revenue.

While it’s perfectly possible to build a business by dominating one market, the greatest rewards come from branching out to a worldwide audience. Localizing your app can help you engage with users in any region.

But what exactly is mobile app localization, and how does it work? In this guide, we will answer all your burning questions.

What Exactly Is Mobile App Localization?

In simple terms, mobile app localization (you may see localization also written as l10n) is the process of adapting your app to the language and culture of a given location. This includes both the content within the app, and the app store content used to promote your product.

The process usually involves a number of different steps, both creative and technical.


Translation is an important part of localization. Users need to understand the copy within your app in order to use it effectively.

There are essentially two types of translation: machine and human.

Machine translation is performed by intelligent algorithms. Because the process is almost instant, you can use machine-generated translations as placeholders in mockups and early versions of your app. Introducing translated content at this stage prevents problems with localization down the line.

Later in the development process, it’s a good idea to invest in human translation. This takes longer, but professional translators are more accurate and sensitive to subtleties than artificial intelligence is.

Another variable is how translations are added to your app. Some platforms require you to complete this task manually, while others automate the process.

Adding translations by hand takes time, so an automated solution is usually the better option. When combined with machine translation, this workflow provides near-instant localization during development.

Some platforms allow you to switch to human translation for the production stage, while maintaining the same automated workflow.

Locale Optimization

Even when users share a common language, they may use it very differently. For example, there are countless differences between the vocabularies of U.S. English and British English speakers.

In development, each language and location pairing is known as a locale. Here are some common examples, with their universal codes:

  • en_US (English – United States)
  • en_GB (English – United Kingdom)
  • en_AU (English – Australia)
  • es_ES (Spanish – Spain)
  • es_US (Spanish – United States)
  • es_MX  (Spanish – Mexico)

In order to provide users with a good experience, it’s important to adapt your UI copy for each locale — including the culture. This will ensure that the interface feels native to users in every location.

What Are the Benefits of Localizing Your Mobile App?

Updating your app for multiple regions might seem like a significant project. However, the numbers show that localization is worth every dime.

The three countries with the highest mobile app revenue in 2020 were China, the United States, and Japan. India was the fastest-growing market, with the Philippines, Thailand, Indonesia, Saudi Arabia, and Egypt not far behind.

What Are the Benefits of Localizing Your Mobile App?

Localizing your app for each of these regions can help you connect with hundreds of millions of potential customers. Benefits include:

  • Increased brand awareness
  • Easier for users to find your app
  • More downloads over time
  • Better active user retention

How to Create a Mobile App Localization Strategy

As with any major upgrade to your app, successful localization starts with careful planning.

While it might be tempting to rush into every major market, it’s usually more beneficial to master a few key locales rather than deliver sub-standard localizations for a hundred markets.

As such, the first step in developing your localization strategy should be identifying your target markets.

Consider Your Existing Users

A good place to start your research is with your current user base.

Analytics can reveal the location and preferred languages of your existing users. Any locale that features prominently in user share will be a good candidate for localization.

Aside from raw data, it’s possible to learn a lot from user feedback. Look for app reviews that talk about accessibility or ask for a version of your app in a particular language. Sometimes, the signs aren’t that obvious; you may need to look at where in the world the reviews and feedback are coming from.

Market Research

Aside from your own stats and feedback, market research can reveal which audiences are likely to offer the greatest return on investment.

Sites such as Sensor Tower and App Annie offer a wide selection of helpful metrics. For instance, research from App Annie shows there were nine markets in Q1 2021 where smartphone users spent an average of four hours or more each day using mobile apps. These platforms also offer more specific insights, such as growth markets for various app types.

Studying your competitors is another good way to get some sense of direction. If the market leader has localized for a specific region, it might be worth following suit.

Creating a Plan

Having identified the markets you wish to target, the next step is creating a plan of action.

In general, localizing your app for one location at a time is advisable. This makes it easier to focus on a specific market, and it allows your team to cover all the locales within that region — so no users will be left out.

Choose a Professional Translation Service

As mentioned above, machine translation is a useful tool for localizing your app during development.

However, it’s generally a good idea to utilize professional human translation for the production release version.

Why? Although algorithms are smart, they occasionally misinterpret the meaning of words. Human translators can also make better decisions when it comes to culture and customs.

For this reason, the final part of your planning process should be dedicated to finding a translation professional. There are countless service providers, some more accustomed to mobile app localization than others. Here are a few popular examples:

OneSky specializes in app localization, providing an end-to-end solution that covers 19 file formats and over 50 languages. The service has over 1,000 human translators, along with technical solutions to make localization smoother.

Always Provide Context

Whichever solution you choose, it’s important to provide your translators with context. Copying and pasting content from your app into a Word document removes key clues about the meaning of your words.

An example: does “the right channel” mean the correct channel or the channel on the right of the interface?

By providing context, you will ensure your translator finds the appropriate phrase in their own language.

Beyond Translation

Translating your content from one language to another is the most basic form of localization. But to thrive in foreign markets, you will need to go further.

Cultural differences often create an invisible ceiling for marketing campaigns, and even a brand name may lose its resonance when translated directly.

For example, in the world of entertainment, it’s common for entire franchises to be renamed to suit different markets.

Take the popular Spanish Netflix show, La Casa de Papel. Translated literally, the title means “The House of Paper.” But in English-speaking markets, the show is known as Money Heist, and German viewers enjoy Haus des Geldes (“House of Money”).

beyond translation

While app stores generally do not allow this level of creative freedom, it’s worth working with an experienced translator to optimize your content and branding for each market.

How to localize your mobile app

Having completed your research, identified your target markets, and chosen a translation service, it’s time to get on with localizing your app.

The exact process may vary, but your localization roadmap will probably look something like this:

  1. Submit content for translation
  2. Implement the localization
  3. The testing phase
  4. Optimize for new markets
  5. Launch localization for users

Let’s take a closer look at each of these steps.

Submit Content for Translation

In most cases, the best way to submit content for translation is through a strings file. If your app doesn’t already have one, you can simply create a new text file and add all relevant content.

Most localization services support the XML and .strings file types. As a convenient alternative, OneSky allows developers to import in-app content directly through an API.

To assist the translator, you may wish to insert comments that provide context. OneSky even allows you to attach screenshots. Maintaining communication with your translator throughout the process is another way to avoid mistakes.

Of course, strings do not hold all of the content within most apps. Localization should cover date formats, currencies, images, audio clips, video, animations, and more. In addition, App Store and Google Play listings will need to be translated.

Wherever possible, text should be separated from audio-visual elements. This makes the translation process smoother, and allows you to implement different localizations without redesigning graphics, for example. Dates, formats, and currencies can be handled by specialized libraries.

Submit Content for Translation

Implement Your Localization

Once translation is complete, you should receive a foreign-language version of the file you submitted. Some platforms allow you to download the translation in other file formats, although this may cause problems with syntax.

If you go down the strings file route, you should be able to add the localized version directly to your app. OneSky also offers direct importing via API and mobile plugins.

If your app is largely the same on both iOS and Android, with OneSky you can create a shared project. This means that you only need to translate your content once, and then download the relevant file type for each platform.

App Store Localization

To update your iOS app with new localization, you will need to visit App Store Connect and navigate to My Apps > App Information.

Here you will be able to create a new version of your app and select the locales it is optimized for.

Google Play Localization

On Android, localization happens through your Google Play Console.

You don’t need to create a new version — just head to Store Presence > Store Listing and enter a localized title and description.

The Testing Phase

The process of localization can sometimes alter how your app works. For instance, a change in the length of strings may affect the interface layout.

For this reason, it’s a good idea to conduct “smoke testing” — where a member of your team uses the app without understanding the translation. Such tests can reveal performance issues, which you can fix before the next stage of testing.

You may then wish to soft-launch the newly localized version of your app with a small group of testers from the target locale. This should pick up any glaring discrepancies in the translated content. OneSky offers on-device testing as part of the end-to-end workflow.

Optimize for New Markets

After making the effort to localize your app, it’s worth spending some time optimizing your app listing for your new markets.

Along with the title and descriptions, it’s worth considering whether you need to change your app logo, preview screenshots, and videos for your target market. It might be worth consulting a specialist for help with this.

Just as importantly, you will want to update your App Store and Google Play keywords. This will ensure that users in your new market will find your app.

Be aware that the App Store only allows you to use any given keyword once throughout all your regional versions. In addition, keywords won’t be combined across localized listings.

Launch Localization for Users

Having completed all your pre-flight checks and optimized your listings, it’s time to launch!

Pay attention to feedback coming from users in your new market. They are likely to flag any remaining areas for improvement in your localization.

localize your mobile app

Simplify mobile app localization with OneSky

As this guide proves, good localization takes research, planning, and time spent on adapting your app. However, the rewards are worth many times the resources you invest.

If you would like to streamline the process, OneSky can help. Our platform offers an end-to-end solution to help you translate, implement, test, and launch localized versions of your app.

Want to give it a try? Sign up here to get started!

Greg Sung

Co-founder & CEO, OneSky

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1 Response

  1. smith Johnes says:

    Thank you for sharing such a informative Guide to mobile app localization.
    For more information on mobile app development, please visit the link.

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