Most apps never get translated. Not because nobody cares — because i18n is a second job. You invent keys, keep a catalog in sync, rename cta.submit_v2, send a spreadsheet somewhere, wait, merge, miss a string, do it again. So the app ships in English and stays that way.
Duckalization is a localization library for TypeScript apps that makes most of that go away. You write the English in your code. That string is the message. No keys. An agent does the translation.
__('Sign in')
__('Welcome back, {name}', { name })
__('Book', { context: 'verb' })
__({ one: '{count} item', other: '{count} items' }, { count })The name comes from the call shape. Squint at __('') and it looks like a duck face.
pnpm add @duckalization/react
pnpm add -D @duckalization/cliWrap copy as you write it. duckalize extract builds the catalog from those strings. duckalize translate brief writes a work order for whatever is still missing. Hand that JSON to an agent. The agent returns translations. apply checks them before they touch your catalog.
The CLI never calls a model. It writes the brief, validates the result, and stays out of the way. The thing you point the agent at is llms.txt: how to write __() calls, how to extract, how to translate a brief, how to wire a new app. That’s the contract.
Missing translations fall back to the inline English, so a partial catalog is still shippable. You can ship the Spanish you have today and let an agent fill the gaps later.
That’s the 99%. The 1% is wrapping the strings and glancing at what the agent wrote.
The package is at github.com/soska/duckalization. Start with llms.txt if you’re an agent. Start with the README if you’re not.