ui_locales gives a hint about the desired display language of the login UI

Integrators will need to supply the “ui_locales” parameter when creating the authorization URL that starts the consent flow, as described in the specification here https://openid.net/specs/openid-connect-core-1_0.html#AuthRequest.

To enable Finnish language, the “ui_locales” must have the value “fi-FI”.

Using the ConsoleClientExample code that used is availble GitHub, the first part of the code would look like this:

var client = new OidcClient(OidcClientHelpers.ConfigureOidcClient(RedirectUri));


var extraParameters = new Dictionary<string, string>


    {"ui_locales", "fi-FI"}



var state = await client.PrepareLoginAsync(extraParameters);


The above is simply using IdentityModel, so it also applicable to other implementations in C#.