Introduction to app localization in iOS and Android

Users enjoy apps that are native to them in terms of language and culture. As of 2014, over 30% of mobile app users had stopped engaging with apps that weren't localized to their needs.

As a mobile app developer or product manager, your primary goal should be to maximize your app's potential reach and effectiveness. If you're not localizing your app, you're not only limiting its global scope — you're also leaving money on the table.

What is mobile app localization?

Mobile app localization is the method of adapting your app to meet the needs of a particular language, culture, or desired population.

The goal of localization (abbreviated as “l10n”) is to make it easier for people to use an app and have an enjoyable experience while using their native language and incorporating their cultural nuances.

Understanding the differences between localization, translation, and internationalization

When planning for localization, translation and internationalization are two concepts that teams often have to contend with. While some people use these three concepts interchangeably, there are stark differences that teams should be aware of before embarking on any localization project.

Below, we'll explore how translation and internationalization differ from localization and the importance of each one.

Localization vs. Translation

From our earlier definition, you may think localization and translation are similar—but in reality, they mean separate things.

Translation is one of the initial steps involved in localization. However, localization goes beyond the mere translation of app copy into the desired language. Localization accounts for both linguistic and native standards.

To help you understand this even better, let's consider the following example:

Imagine you have a mobile app for delivery. For an American audience, you can pass this message: “Five pounds of flour cost $15 and will be delivered to you on 06-12-2021.

Translating this to Spanish will become: “Cinco libras de harina cuestan $15 y le serán entregadas el 06-12-2021.”

However, this translation won't have much meaning for users in Mexico (despite being a Spanish locale) because:

  • The currency in Mexico is pesos, not U.S. dollars
  • The date format in Mexico is dd-mm-yyyy as opposed to mm-dd-yyyy used in the U.S.
  • The metric system (kg) is used in Mexico for weight, not the imperial system (pounds)

When you localize your app, you're adapting its content and copy to a new region or country. You want your audience to feel like your mobile app was made specifically for them and to suit their unique needs.

Localization vs. Internationalization

Internationalization and localization are often used in the same context. But again, they are separate notions.

Internationalization (abbreviated as “i18n) is the process of preparing your app to adapt easily to different locales, languages, or regions. In contrast, localization is the process of actually adapting your app to a different language or region using the infrastructure set up by internationalization.

For a better understanding, think of it this way: internationalization lays the groundwork for localization. It involves all the best practices and methodologies that teams need to follow for a smoother app localization process. When internationalization is adequately carried out, teams will complete the localization process quicker.

In practice, an excellent internationalization plan is to separate your content or text from your codebase. When you do this, you dynamically load the content, and it makes it easier to localize your app for different locales.

Source: CleverTap

Why mobile app localization is critical for your business

Let's face it—mobile apps have become day-to-day tools for many of us. In 2020, consumers downloaded 247 billion apps. It's safe to say that if your app is only available in a single language, you're missing out on creating a delightful experience for your global audience.

In reality, localization has some drawbacks, such as prolonged development time and cost. For example, every new feature or little text change will now take more time to develop. And while this time add is often linear, it can be significant. As a result, some developers avoid app localization at all costs.

When it comes down to it, despite these drawbacks, there are still numerous reasons why you should consider app localization.

Increased app downloads

The effect of localization on app downloads is remarkable. A study from Distomo showed that "localizing iPhone app text resulted in significantly more downloads — 128% more per country..." Localization is definitely a great strategy to rank your app higher and get more downloads in a particular region.

Improved user experience

If users struggle to understand your app, they will stop using it. Creating an app in a country's native language and culture is more engaging. For example, the user interface must be straightforward, offer quick access to app functionality, be pleasing to the eye, and be easy to navigate. Select the colors, fonts, and layout that deliver a better user experience in that region.

Increased ROI

Although localization is expensive, the return on investment (ROI) for localizing your app is high. Since every geographical audience has its perks, when you localize your app, it encourages more people in that country to download it from the app stores (both Google Play and Apple’s App Store). Companies that localized their apps saw a 26% increase in revenue for each country within just one week of offering a localized app.

Expanded customer base

Mobile apps are gradually becoming marketing tools for companies. The more languages and cultures your app caters to, the stronger your brand visibility will be. When more customers know your brand, marketing to them and growing your customer base will be a lot easier.

What should mobile app localization include?

Although localization sounds simple, it is not. It is time consuming and, most times, challenging. As such, it is not a one-size-fits-all process. Your business needs and target audience will usually determine the details and extent of your app localization.

An excellent approach to localization is to think about how to include different dialects of the same language, often called locales. For instance, both Mexico and Spain are Spanish locales but localizing your app in Mexico will be different from localizing your app in Spain.

The most common factors to consider when planning your app localization are:

Right-to-Left (RTL) language support

Arabic is the most common RTL language. When localizing for RTL languages, you'll need to know the elements to mirror and those not to mirror. You'll also need to think about text alignment, page formatting, and the overall layout of each screen.



Color conveys various meanings for different groups of people and cultures. For example, red in Western cultures symbolizes passion and excitement, while in South Africa, red represents mourning. Proper research of colors and their meanings should be done when preparing for localization.

Measurement units

Localizing a measurement unit requires applying the measurement standard in that region for users to easily understand and navigate the app. While most countries use the metric system, some don't, and you'd need to consider this when planning app localization.

Fonts and special characters

When localizing text content, special characters such as the ampersand and colon pose a problem during translation. Ensure fonts used in your app support all the required special characters and umlauts for each language.

Number formats for date and time

People in different countries write the date and time in particular forms. For example, in the U.S., the date format is mm-dd-yyyy, while in other countries, it could be dd-mm-yyyy. The same is true for time formats. Some countries use the 12-hour time format (am/pm), whereas others use the 24-hour format. Because of this, it is essential to examine the date and time based on the locale.


Currency is formatted differently in several countries, and it could be confusing for your users to see prices in the wrong formats. For instance, some countries place the currency symbol to the left of the number, while others place it to the right.

Also, symbols like the dollar ($) represent the currency in Canada, Australia, and the United States, among other countries. It is best to use ISO codes with currency symbols to make currencies more understandable.

What is the process to localize mobile apps?

The steps to localize your mobile app are as follows:

1. Decide on locales to support

The first step in localization is determining which language and region you'd want to localize your app. The Google Play Store currently supports 49 languages, while Apple's App Store supports 40 languages. With so many languages to consider, you'd probably ask, "How do I decide on the locale to support?"

While this is mainly a business decision, an excellent way to approach this is to check which languages have the most app downloads. With this, you'll get a clear idea of the language and region to localize your app.

Source: Statista

2. Use professional translators

Translation is more technical than it appears because it not only requires conveying a message across different languages but also involves choosing the exact words that appeal to your target audience.

Utilizing professional translators for your app is beneficial because they have more experience dealing with varying demographics and can adapt your translations to suit your particular locale.

Tip: Avoid using Google Translate when translating your app because it doesn't always provide accurate results.

3. Hire freelance localization experts

Freelance localization experts are a great alternative to professional translators and agencies because they usually have less expensive rates. You can find freelancers on job boards like Upwork (formerly oDesk or Elance).

Running an initial test project is always a good idea to ensure the results you'll get are not similar to Google Translate. This also helps you ascertain the freelancer's expertise before committing to them.

4. Leverage localization tools

Localization tools enable teams to manage the localization process quickly. A tool like Localazy helps developers speed up the translation process and improve its accuracy. Localazy is now available in the Bitrise Step Library. Check out how to add the Localazy Step to your Workflow here.

5. Optimize your app store listing

Optimizing your app store listing involves using the correctly translated name, descriptions, and relevant images. It also requires tweaking your app's metadata. A great strategy to optimize app store listings is to check out competitors' data such as titles, subtitles, and app descriptions and then mirror these keywords in your app listing.

What does app localization look like in iOS and Android?

While localization of mobile apps for both Android and iOS have some similarities, they differ in some ways. For instance, iOS recommends exporting files that need to be localized from your Xcode project, while for Android, resources are a vital part.

Android localization

Sameer Samat, Google’s Vice President of product management, recently disclosed that there are more than 3 billion active Android devices. This implies, if you localize your app in the Google Play Store, you're potentially able to reach a large percentage of this number.

Android also provides a localization checklist you can take advantage of to maximize your app's distribution potential. This is a great starting point when preparing for app localization on Android.

iOS localization

With over 1 billion users, Apple’s App Store is now available in 175 regions and supports 40 languages.

Apple tools such as Xcode 11, Apple APIs, and Unicode all help in the localization of your app. It is good practice to separate the content to be localized into two different types of files:

  • File with strings extension: This will group all single strings and formats.
  • File with .stringsdict extension: This will group strings that contain plurals or contextualized variables.

Apple also provides a guide on localization for developers.

How can I test localization in mobile apps?

Localization testing is a technique in which an app's content, user interface (UI), functionality, and usability are tested for a particular country, locale, or culture. The goal of localization testing is to identify flaws in translation or concerns with cultural differences.

For instance, imagine that you've built an app that has English and German versions. You've completed the localization process and feel pretty confident that the grammar and cultural differences have been adequately addressed. However, you suddenly realize that the length of button text in German exceeds the button text in English. Localization testing prevents scenarios like this and ensures that the overall app is native to that region.


There are two ways of carrying out localization testing:

Manual testing

When it comes to manually testing apps for localization, QA teams should focus on these core areas:

  • Content: Confirm that the translation from one language to the other is accurate.
  • UI elements: Check the app to recognize problems with the layout and design.
  • Functionality: Verify that the app functions as expected irrespective of language.

Automated Testing

While most localization testing needs to be performed manually, consider creating automated tests to check:

  • The layout of UI elements: Automated testing can confirm if your design elements appear in the right place after localization and that all elements stay intact after language translation.
  • Text: Every word has an associated translation for each of the supported languages. Test automation can validate that the right words for each language are maintained during translation.

An excellent approach to visual UI testing (also called Screenshot testing) for Android apps is to utilize Applitools with Bitrise. The benefits of automated localization testing over manual testing is that we can speed the testing process with different screens at the same time with different languages and different devices to make sure that we cover the most critical test cases. In contrast, manual testing is time consuming and takes a huge effort from the QA team to cover all the critical scenarios or the most essential features in the app. 

With Bitrise's automated testing solution, you can run localization tests that identify translation glitches during the development process.

Localize your app to reach a wider audience

The facts are undeniable; mobile apps are a huge part of our lives. If you'd like to expand into new markets, you shouldn't overlook localization. It can be beneficial for boosting app downloads, user retention, and loyalty. If done precisely, localization is also one of the ways to ensure more revenue for your business. Get a deeper insight into mobile app localization challenges and how to navigate them here.

Localization is, however, not a one-off activity. Each time you make changes to your mobile app, you'll need to modify these changes to suit other locales. For thorough localization testing, teams should combine manual with automated tests. 

Bitrise offers you a seamless way to automate localization tests each time, using a CI/CD pipeline. When integrated with Localazy, your app can reach a wider audience. Get started today for free.

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