App localization
for iOS, Android & Web

Internationalization (i18n) is the engineering work that makes your app capable of supporting multiple languages — externalizing strings into resource files, handling plural forms, formatting dates and currencies per locale, and designing layouts that accommodate variable-length text. It is a one-time foundational investment in your codebase.

App localization (l10n) is the ongoing process of adapting your application for each target market. It includes translating UI strings, localizing push notifications, adapting app store listings (ASO), adjusting imagery and iconography for cultural fit, and ensuring the full user experience feels native. Localization builds on top of internationalization, and it continues with every release.

In practice, i18n and l10n work hand-in-hand. A well-internationalized app makes localization fast and repeatable. Tools like SimpleLocalize bridge the gap — you upload your i18n resource files, translate them in the online editor, and deliver updates via CDN or file export, keeping both processes seamless.

Mobile app localization is the process of adapting an iOS or Android application for users in different languages and regions. It covers the entire user experience: in-app UI strings, onboarding flows, push notifications, in-app purchase descriptions, error messages, and app store metadata (title, subtitle, description, keywords, and screenshots).

Unlike web localization, mobile l10n must account for platform-specific file formats (Localizable.strings for iOS, strings.xml for Android, .arb for Flutter), strict character limits on smaller screens, and the friction of app store review cycles for every update. This is why CDN-backed translation delivery is so valuable — it lets you update translations without submitting a new binary.

App Store Optimization (ASO) is the process of improving your app's visibility in app store search results. Localization is one of the most powerful — and often overlooked — ASO levers. By localizing your app title, subtitle, keywords, and description for each market, you multiply the search terms your app ranks for across dozens of storefronts.

Apple's App Store supports 40 languages, and Google Play over 75. Apps that localize their metadata see significantly higher organic impressions and download conversion rates in non-English markets. Combine ASO localization with translated in-app content for maximum impact — users who download a localized listing expect a localized experience inside the app as well.

React Native apps typically use react-i18next or FormatJS (react-intl) to load translations at runtime from JSON files. The localization workflow looks like this:

• Externalize strings — wrap every user-facing string in a t() function and organize keys into JSON translation files per locale.
• Upload to SimpleLocalize — use the CLI to push your base-language JSON file. New keys are detected automatically.
• Translate & review — auto-translate with DeepL or OpenAI, then refine in the online editor with your team.
• Deliver translations — download updated JSON files for bundling, or fetch them from the CDN at app startup for instant updates.

This workflow keeps translations in sync with your codebase and eliminates manual copy-paste between spreadsheets and source files. Read our continuous localization guide for the full CI/CD setup.

Yes. SimpleLocalize's Translation Hosting delivers translations via a global CDN. Your app fetches the latest translation files at startup or on demand, so you can fix typos, update marketing copy, or add new languages without submitting a new build to the App Store or Google Play.

JSON-based frameworks like React Native and Expo can use CDN-backed translation delivery today: just point your i18n loader at the hosted JSON endpoint. For native iOS (Swift) and Android (Kotlin) apps, dedicated SDKs with zero-config OTA support are coming soon.

Start by internationalizing your app: externalize all user-facing strings into translation files (JSON, ARB, Strings, XML, etc.). Then create a free SimpleLocalize project, upload your base-language file, auto-translate into your target languages, review the results, and publish via CDN or file download. The entire process takes minutes to set up. See our getting started guide for a step-by-step walkthrough.