Make your sign-in experience feel native to every user. In this tutorial, you’ll learn how to use the standard OIDC parameter ui_locales to set the runtime language of Logto’s sign-in UI and related emails.
Logto already supports multi-language content and auto-detection, but there are times you want to explicitly pick the language for a specific interaction:
Besides, ui_locales is a standard parameter supported by many identity providers and SDKs.
uiLocales (e.g., "Requested languages: {{uiLocales}}")Learn more in the reference: UI locales docs.
Optional but handy:
Logto SDKs let you pass extra OIDC parameters during sign-in. Add ui_locales in extraParams:
Notes:
fr-CA, otherwise fr, otherwise en).ui_locales with other standard/custom parameters (e.g., login_hint, organization_id, or first screen directives).If you’re wiring the OIDC authorization request manually (or via a generic OIDC client), add ui_locales directly:
When an interaction triggers an email (e.g., verification code), Logto resolves language in this order:
ui_locales (first supported tag)Accept-Language headerThen Logto tries to find a custom email template that matches the resolved language and template type; if none is found, it falls back to the connector default.
Provider-managed templates (e.g., Postmark, HTTP Email): Logto passes both uiLocales and locale to your provider. If ui_locales is present, locale uses the first supported tag from ui_locales.
See: Email template localization.