Verified against the LocalePilot source code on 30/10/2026 (commit b84b323). Microsoft Translator and Google Cloud Translation require LocalePilot Pro; LibreTranslate can be used without it.
What is sent
One request per text, holding:
- the source text, as HTML. Placeholders are replaced by numbered markers flagged as not to be translated, then put back;
- the source and target language codes.
Messages with ICU plurals or selections are not sent: they need an AI model. The Before you launch panel lists the selected keys and reminds you that they are not sent.
What is never sent
- Key names, descriptions and groups.
- The current translation, neighboring keys and translations in other languages.
- The glossary and the project's Translation context. Use approved glossary has no effect with these services.
- Your files, their names and their paths, and the name of your project.
- Store listings: Adapt with AI needs an AI model.
- Translations to audit: the AI audit needs an AI model.
What stays with the provider
LocalePilot creates nothing in your account with these services. How long Microsoft or Google keep the texts they translate depends on their terms and on your account settings.
Microsoft Translator
- Address:
https://api.cognitive.microsofttranslator.com, version 3.0 of the API. It cannot be changed. - API key: required, sent in an
Ocp-Apim-Subscription-Keyheader. If you fill in Azure region (empty for a global resource), the region is sent in anOcp-Apim-Subscription-Regionheader. - Test translates the word “Hello” from English to French.
Google Cloud Translation
- Address:
https://translation.googleapis.com/language/translate/v2, the Basic (v2) edition of the API. It cannot be changed. - API key: required. As this version of the API expects, it is sent in the address of the request (
?key=). When a network error occurs, LocalePilot does not show or log that address, so the key does not appear in error messages. - Test translates the word “Hello” from English to French.
LibreTranslate
- Address:
http://localhost:5000by default, a server on this Mac. With this address, nothing leaves your Mac. - The Service address can be changed, for example to a public LibreTranslate server or one on another computer. The texts then leave your Mac and go to that address. The Before you launch panel shows the real address and whether it is local, on your local network, remote or an unknown destination.
- API key: optional. If you add one, it is sent in the body of each request (
api_key). - Test translates the word “Hello” from English to French on the configured server.
Where the API key is stored
Add your key in Settings, AI provider, with Add a key. It is stored in the macOS Keychain, never in LocalePilot's settings file. The Azure region is not a secret, so it is saved with the other settings.
Options that change what is sent
- Translate automatically with …, in Add a language: checked by default, it translates a new language as soon as you add it.
- A text already translated in the same conditions is taken from a local cache and is not sent again.
The comparison with the other providers is on What is sent.