This package is implemented as a FastAPI dependency which initializes translations using the gettext module and makes them available throughout the request lifecycle using a Conext Variable.

uv add fastapi-i18n

A locale directory adhering to the GNU gettext message catalog API containing translated messages. See chapter on Babel for more details.

export FASTAPI_I18N_LOCALE_DIR="paht/to/locale/dir" export FASTAPI_I18N_LOCALE_DEFAULT="de"

from fastapi import FastAPI, Depends from fastapi_i18n import i18n, _ app = FastAPI(dependencies=[Depends(i18n)]) @app.get("/") def root(): return _("Hello from fastapi-i18n!")

Set Accept-Language header for requests to get a translated version of the response.

For a complete example see tests.

Babel is not a dependency of FastAPI i18n, but it is useful for working with GNU gettext message catalogs.

To add new locale and use babel to extract messages from Python files run:

echo "[python: **.py]" > babel.cfg pybabel extract -F babel.cfg -o messages.pot . pybabel init -i messages.pot -d locale -l de # Now translate messages in locale/de/LC_MESSAGES/messages.po # Then compile locale: pybabel compile -d locale

To update existing locale run update instead of init run:

pybabel extract -F babel.cfg -o messages.pot . pybabel update -i messages.pot -d locale

• Move to GitHub
• Support configuration via pyproject.toml
• Validate locale string
• Support setting locale using query parameter
• Support configuration of domain (currently defaults to "messages")

• FastAPI babel