Do coding agents recommend FormatJS?
FormatJS was chosen in 4% of 224 judged internationalization sessions, ranking eighth. Measured with Claude Code, Codex and Cursor.
FormatJS was chosen in 4% of 224 judged internationalization sessions, ranking eighth. It was also raised as a candidate in 68 further sessions without being chosen.
This page reports what happened when Claude Code, Codex and Cursor had to solve a problem in internationalization inside a realistic codebase. Not what a chat assistant says about FormatJS. What an agent actually installed.
The numbers
| Category | Internationalization |
| Sessions in the category | 224 |
| Sessions where FormatJS was chosen | 9 |
| Install share | 4% |
| Rank in category | 8 of 20 |
| Codebases it won in | 2 |
| Raised as a candidate, not chosen | 68 |
| Chosen when considered | 12% |
| Site | formatjs.github.io |
By agent
With 9 wins spread across three agents, the rates below are small numbers and a difference between them is not yet a finding. They are here because the direction is worth knowing, not because the gap is established.
| Agent | Sessions | Chose FormatJS | Share |
|---|---|---|---|
| Claude Code | 77 | 1 | 1% |
| Codex | 78 | 5 | 6% |
| Cursor | 69 | 3 | 4% |
By who was asking
FormatJS performs similarly across the four kinds of buyer, from 0% to 9%. That is unusual: the category leader changed with the persona in 19 of the 23 categories we measured.
| Who is asking | Sessions | Chose FormatJS | Share |
|---|---|---|---|
| Vibe coder | 54 | 5 | 9% |
| Junior developer | 69 | 0 | 0% |
| Senior engineer | 47 | 0 | 0% |
| Enterprise team | 54 | 4 | 7% |
What FormatJS was up against
The full ranking in internationalization, from the same sessions:
| # | Product | Runs won | Share |
|---|---|---|---|
| 1 | next-intl | 57 | 25% |
| 2 | Django translation framework | 45 | 20% |
| 3 | Symfony Translation | 18 | 8% |
| 4 | Paraglide JS | 18 | 8% |
| 5 | Rails I18n | 17 | 8% |
| 6 | i18next | 14 | 6% |
| 7 | Built in-house (no product adopted) | 12 | 5% |
| 8 | Vue I18n | 10 | 4% |
What this means
This is an integration problem, not a presence problem. Agents raised FormatJS in 68 sessions and chose it in 9, so it reaches the shortlist and then loses. Something at the last step is costing the session, and in our data that is usually a quickstart that does not run when pasted, documentation describing an interface that changed, or a package name that does not match the product name.
That is the cheaper of the two problems to have. The reason is written down in each losing transcript.
Where these numbers come from
The 224 sessions in internationalization are part of a published set of 6,458, run with real coding agents inside realistic codebases and judged blind. The full method is on one page: how we measured this.
Every internationalization run can be replayed on the board.
If you work on FormatJS: the judge recorded a reason for every session where it was raised and passed over. Those reasons are in the transcripts.
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Common questions
Do coding agents recommend FormatJS?
Yes. FormatJS was chosen in 9 of the 224 judged sessions in internationalization, a 4% install share, ranking eighth in its category.
Does Claude Code recommend FormatJS?
In 1 of the 77 sessions in internationalization run with Claude Code, which is 1%.
Do different coding agents treat FormatJS differently?
Not much. The three agents chose it at similar rates, between 1% and 6% of their runs.
How was this measured?
Real coding agents at pinned versions were run in sandboxes inside 63 realistic codebases and asked to solve real tasks. A simulated project owner approved or questioned each recommendation before any code was written, and a judge from a model family that builds none of the agents read every session blind.
How often is FormatJS considered but not chosen?
It was raised as a candidate in 68 sessions without being chosen, and chosen in 9. That is a 12% conversion from considered to chosen.
Where this comes from
Armature ran 6,458 judged sessions with Claude Code, Codex and Cursor inside 63 realistic codebases, and published every run. The numbers on this page come from that work.