App localization tool

An app localization tool that ships new languages without breaking the build

Send string files from your repository or current TMS. LanguageOps translates them with AI that follows your glossary, style guide and UI context, protects variables and markup, runs QA, and returns files in the same format and key structure.

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  • Key structure preserved
  • Glossary and UI tone enforced
  • Works alongside Lokalise and Phrase
Why app strings are different

Short strings, very little context, and a build that has to compile

A button label is two words with no sentence around it. The same English word can be a noun on one screen and a verb on the next. Variables, plurals and markup sit inside the text, and one broken placeholder can crash a screen. A good app localization tool has to supply context and protect structure, not just translate.

  • Structure in, structure out

    Keys, nesting, comments and file layout are preserved. Only translatable values are extracted, and the target file mirrors the source.

  • Consistent UI terminology

    A shared glossary keeps “Settings”, “Sign in” and your feature names identical across every screen, platform and release.

  • Checks before merge

    QA flags broken or missing tags, changed numbers and unapproved terminology before translated files reach your repository.

App localization by the numbers

What 338,859 shipped UI translations tell you

We measured every shipped translation in Mastodon, Signal and WordPress across 27 languages. Translated UI text grows, most strings are tiny, and variables break even in mature projects.

How much longer translated UI text runs than English

Change in visible characters, 338,859 shipped translations in Mastodon, Signal and WordPress. The thin line spans the lowest to highest of the three apps.

  1. French +32%
  2. German +28%
  3. Spanish +24%
  4. Italian +23%
  5. Dutch +20%
  6. Portuguese (Brazil) +16%
  7. Polish +16%
  8. Swedish +11%
  9. Japanese −45%
  10. Chinese (Simplified) −66%

All 27 languages, method and data

1 in 13

French UI strings at least twice as long

1 in 13 French UI strings and 1 in 17 German strings are at least twice as long as the English, so a layout sized exactly for English will truncate or wrap them.

Original research LanguageOps UI string study, 23 October 2026

All industry statistics

53–65%

UI strings of 20 characters or fewer

53–65% of app UI strings are 20 characters or fewer, with a median of 16–19 characters, so most strings give translators very little text to work with.

Original research LanguageOps UI string study, 23 October 2026

All industry statistics

1 in 8

UI strings containing a variable

11.8–14.2% of app UI strings contain at least one variable placeholder such as %s or {name}.

Original research LanguageOps UI string study, 23 October 2026

All industry statistics

1 in 950

Shipped translations with a broken placeholder

About 1 in 950 shipped translations that contain a placeholder drop, add or break it (47 of 44,495), across three mature, widely translated open-source apps.

Original research LanguageOps UI string study, 23 October 2026

All industry statistics

50

App Store listing languages

App Store Connect supports localised app metadata in 50 languages, after adding 11 in March 2026, ten of them Indian languages.

Apple Developer News, 31 March 2026

All industry statistics

76%

Online shoppers who prefer their own language

76% of online shoppers prefer to buy products with information in their native language.

CSA Research, Can't Read, Won't Buy – B2C (8,709 consumers, 29 countries), 7 July 2020

All industry statistics

Continuous app localization

How strings move from code to every language

  1. Collect

    Bring in the strings

    Upload resource files, connect a GitHub repository, or pull keys from an existing Lokalise or Phrase project.

  2. Translate

    AI with your context

    Key names, developer comments, glossary, style guide and translation memory are applied, so short UI strings are translated for the screen they appear on.

  3. Review

    Human review where it matters

    Native reviewers check onboarding, paywalls, store listings and legal text in the editor. LQA scoring tells them where to look first.

  4. Ship

    Return and release

    Export files in the original format, open a pull request, or push translations back to the connected TMS for your next build.

App localization features

Everything a product team needs to localize an app

Every feature is included on every paid plan.

  • Developer file formats

    JSON, XLIFF, XML, YAML, PO/POT, Java .properties, .NET RESX and iOS .strings, with key previews and include or exclude rules.

  • Repository workflow

    The GitHub connector (in beta) pulls changed strings from branches and paths and returns translations as a pull request.

  • Works with your current TMS

    Already on Lokalise or Phrase? Use the connectors to bring jobs into LanguageOps for translation and review, then push them back.

  • Translation memory

    Unchanged and repeated strings are reused across releases and platforms, so you only pay attention to what is new.

  • Store listings and marketing

    Localize App Store and Google Play descriptions, release notes, help center articles and onboarding emails in the same account.

  • API, CLI and MCP

    Create jobs and fetch results from CI, scripts or AI coding agents.

Predictable pricing

No per-key or per-language surcharges

Plans are metered by source words and AI tokens, with every feature included. Professional starts at £250/month with five users and unlimited production collaborators.

See pricing

What makes app localization hard

App localization fails in predictable ways. A good tool is designed around each of them:

Problem What goes wrong How LanguageOps handles it
Missing context “Open”, “Post” or “Charge” is translated with the wrong meaning Key names, developer comments, glossary and memory are given to the AI and shown to reviewers
Broken variables and markup {count}, %@ or <b> is edited or dropped, and a screen breaks Inline codes are protected as tags, and QA blocks missing or unbalanced tags
Inconsistent terminology The same feature has three names across iOS, Android and web One shared glossary and memory for every platform and release
Text expansion French and German UI text runs 28–32% longer than English, and 1 in 13 French strings doubles Reviewers see the source and target side by side, and style rules can ask for concise UI copy
Slow release cycles Localization starts after code freeze and holds up the release Changed strings are translated from the branch, and repeated strings are reused from memory
Everything outside the app Store listings, help articles and onboarding emails are forgotten Documents, web content and video are localized in the same account

How to choose an app localization tool

  • Format fidelity: does it return your resource files with keys, nesting, comments and encoding exactly as they were?
  • Developer workflow: can it pull from and return to your repository, or connect to the TMS you already use?
  • Context for translators and AI: are key names, comments and screenshots or descriptions available when strings are translated?
  • Protection and QA: are variables and markup locked, and are broken strings caught before merge?
  • Quality beyond strings: can the same tool handle store listings, help content, marketing and video, so terminology stays consistent?
  • Pricing that scales with you: watch for per-key, per-language or per-seat charges that grow faster than your product.

App localization checklist before your first release

  1. Externalize every user-facing string into resource files. No hard-coded text in views.
  2. Use named variables ({userName}, not concatenated fragments) so translators can reorder sentences.
  3. Handle plurals and gender with your platform’s plural rules rather than if (count == 1).
  4. Leave room for expansion. In our study of shipped app translations, French UI text was 32% longer than English and German 28%, so design flexible layouts.
  5. Add developer comments for ambiguous keys: where the string appears and what it does.
  6. Build a glossary of feature names and UI terms before the first translation, not after.
  7. Localize the store listing and screenshots, which are what users see before they install.
  8. Test with pseudo-localization or a long language before release to catch truncation and hard-coded text.

LanguageOps also localizes the rest of your product content, including documentation and websites, video tutorials and market-specific variants. For engineering-led teams, see the API and the MCP server and CLI.

Frequently asked questions

App localization, explained

What is an app localization tool?
An app localization tool manages the translation of an application’s user-interface strings and related content. It extracts text from resource files, provides a translation and review workflow with glossary and memory, checks the result, and returns localized files that the app can load without code changes.
What is the difference between app translation and app localization?
Translation converts the words. Localization adapts the whole experience for a market: terminology, tone, formality, date and number formats, text length, images, store listings and legal content. A localization tool supports that wider job with context, glossaries, review and QA.
Which file formats do you support for apps?
Common string formats including JSON, XLIFF, XML, YAML, PO/POT, Java .properties, .NET RESX and iOS .strings. XLIFF is also the interchange format used by Xcode localization exports. See the full file formats list, or send us a sample if your format is not listed.
How much longer does app text get when it is translated?
It depends on the language. In our measurement of 338,859 shipped UI translations in Mastodon, Signal and WordPress, French text was 32% longer than English, Greek 30%, German 28% and Spanish 24%, while Chinese used 66% fewer characters. Short labels vary most: 28% of French strings grew by more than half. See the full table for 27 languages.
How do you keep variables and placeholders safe?
Variables, HTML and markup inside strings are extracted as protected tags, so translators and AI cannot edit them. QA then flags any target string where tags are missing, duplicated or unbalanced before the file is exported.
Can AI translate app strings accurately?
AI handles app strings well when it has context: the key name, developer comments, a glossary and examples of your existing UI language. Without context, short strings are ambiguous for any translator. LanguageOps supplies that context, then uses QA and LQA to flag doubtful strings for human review.
Do I have to leave Lokalise, Phrase or Crowdin?
No. Many teams keep their current string-management platform and use LanguageOps for AI translation, review, QA and video or document content. The Lokalise and Phrase connectors move jobs in and out. If you do want to switch, see our Lokalise alternative and Phrase alternative guides.

Localize a real string file today

Send one resource file and your target languages. We will show you the AI output, the QA report and the file you get back.

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