> ## Documentation Index
> Fetch the complete documentation index at: https://hyperlocalise.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Translate Fluent localization files with Hyperlocalise

> Translate Fluent messages and attributes, with explicit limits on terms.

Fluent files describe messages, attributes, and selection patterns for localized interfaces. Hyperlocalise supports a subset of Fluent: message and attribute values are supported, while term definitions and references are rejected.

Supported extensions: `.ftl`.

## Source file

Save this example as `locales/en-US/messages.ftl`.

```text theme={null}
welcome = Welcome, { $name }!
login = Sign in
    .title = Open your account
```

## Configure your files

Use this `i18n.yml` for the example, or add its file mapping to your existing bucket.
See [path templates](/cli/configuration/path-templates) for other layouts.

```yaml theme={null}
locales:
    source: en-US
    targets:
        - es-ES

buckets:
    messages:
        files:
            - from: locales/en-US/messages.ftl
              to: locales/{{target}}/messages.ftl

llm:
    profiles:
        default:
            provider: openai
            model: gpt-5.2
```

## Translate

[Install the CLI](/cli/getting-started/install) and set `OPENAI_API_KEY` in your
project's `.env.local` or shell. You can also configure another
[AI provider](/cli/providers/overview).

```bash theme={null}
hyperlocalise run --dry-run
hyperlocalise run
```

The dry run previews the work. The second command writes translations to the
configured target path and updates the lockfile.

## Behavior and limitations

* Message IDs become keys; attributes become dotted keys such as `login.title`.

* Multiline messages and select/plural patterns remain one value per message or attribute.

* Comments, blank lines, and ordering are preserved in the selected template. Missing top-level messages are appended in sorted order.

* Term definitions such as `-brand` and term references are unsupported and rejected. New attributes cannot be appended to a parent already present in the template.

## Next steps

* [Check translations](/cli/commands/check) before committing generated files.
* [Local translation workflow](/cli/workflows/local-generation) explains repeat runs.
* [Browse all file formats](/cli/reference/formats/overview).

## Related formats

* [gettext PO](/cli/reference/formats/gettext)
* [FormatJS and React Intl catalogs](/cli/reference/formats/formatjs)