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Internationalization: which solutions coding agents choose

next-intl led with about 22% of 500 runs.

500 runs12 apps5 agents4 personasupdated 2026-09-29

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Key learnings

We asked five agents to add internationalization to 12 codebases, 500 runs in all, putting the job in different words and as four kinds of people. The Django translation framework came second at about 19%. Below those two, the wins scatter thin.

38 wins

The framework in the codebase settled some picks

Rails I18n won 38 times, all of them in the Rails marketplace. All 27 wins for Vue I18n came in the Nuxt field service app.

39 of 41

Who asked changed what came back

Enterprise teams put the Django translation framework first in 79 of their 170 runs. Paraglide JS won 41 times in all, and 39 of those came from junior developers.

32 of 58

Rewording the ask often changed the answer

We ran each codebase and agent several times, asked in different words. In 32 of 58 of those sets, the runs did not all land on the same solution.

4 of 263

Named constantly, chosen almost never

Crowdin came up 263 times and won four runs. Lokalise was named 218 times and never chosen. GNU gettext got 165 mentions and no wins.

  • Muse Code and Grok Build CLI led with the Django translation framework; the other three agents led with next-intl.
  • The agents wrote it themselves in 41 runs, about 8%.
  • The simulated user approved every plan, but sent the agent back at least once in 134 runs.
  • The Intl API was named 71 times and never chosen; it is the browser's own formatting API, not a way to translate an app.
Explore every run in the interactive board

The ranking500 runs

ProductWinsShare
1 next-intlnext-intl.dev 110 22%
2 Django translation frameworkdocs.djangoproject.com 96 19%
3 Symfony Translationsymfony.com 41 8%
4 Paraglide JSinlang.com 41 8%
5 Built in-houseoutcome 41 8%
6 Rails I18nguides.rubyonrails.org 38 8%
7 Vue I18nvue-i18n.intlify.dev 27 5%
8 i18nexti18next.com 27 5%
9 FormatJSformatjs.github.io 15 3%
10 Tolgeetolgee.io 9 2%
11 Django translation framework + Babel (Python) 7 1%
12 Weblateweblate.org 7 1%
13 Crowdin + next-intl 4 1%
14 FormatJS + next-intl 4 1%
15 Django translation framework + Weblate 4 1%
16 Crowdincrowdin.com 4 1%
17 Linguilingui.dev 4 1%
18 Phrasephrase.com 3 1%
19 nestjs-i18n + next-intl 3 1%
20 i18next + Phrase 2 0%
21 Mobility + Rails I18n 2 0%
22 Crowdin + Django translation framework 1 0%
23 Crowdin + FormatJS + next-intl 1 0%
24 locizelocize.com 1 0%
25 i18n-tasksgithub.com 1 0%
26 Crowdin + Vue I18n 1 0%
27 Django translation framework + GNU gettext + Weblate 1 0%
28 i18n-tasks + Mobility + Rails I18n 1 0%
29 Intlayerintlayer.org 1 0%
30 i18next + Weblate 1 0%
31 next-intl + Tolgee 1 0%
32 i18next + locize 1 0%

By agent, by persona, by wording

By agent

Codex150 runsnext-intl · 32then Django translation framework · 25
Claude Code113 runsnext-intl · 34then Django translation framework · 23
Muse Code · Muse Spark 1.3108 runsDjango translation framework · 22then next-intl · 18
Cursor103 runsnext-intl · 22then Django translation framework · 20
Grok Build CLI · Grok 4.726 runsDjango translation framework · 6then next-intl · 4

By persona

Enterprise team170 runsDjango translation framework · 79then Symfony Translation · 23
Junior developer115 runsParaglide JS · 39then Vue I18n · 27
Senior engineer113 runsnext-intl · 56then Rails I18n · 38
Vibe coder102 runsnext-intl · 45then i18next · 21

By what the ask stressed

The plain ask460 runsnext-intl · 110then Django translation framework · 73

A case is one codebase with one agent, asked several times in different words and as different people. 32 of 58 cases did not hold to a single solution.

How this was measured

Every number on this page comes from a controlled experiment. We took 12 small applications, asked 5 coding agents (Codex, Claude Code, Muse Code (Muse Spark 1.3), Cursor, Grok Build CLI (Grok 4.7)) to add internationalization to each of them, in several wordings and as an enterprise team and junior developer and senior engineer and vibe coder, and let the agent choose the product. Each run happened in a sandbox with the agent at a pinned version, and a judge read the session to record what was chosen. That is 500 runs. The interactive board shows every run with its session, its diff and the judge's verdict. A simulated user stood in for the owner of the codebase: it read the agent's plan and had to approve it before any code was written; it sent the agent back at least once in 134 runs. Read the methodology and the publications.

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