This page demonstrates the conditional mediation flow where FedCM credentials appear in the browser's autofill menu.

Use Chrome 144 or newer, enable the flag at chrome://flags/#fedcm-autofill.

Annotate your input field with autocomplete="username webidentity" (or autocomplete="webidentity") and the right name attribute values to see the FedCM account in the autofill dropdown, and call the API with conditional mediation:

              
const {token} = await navigator.credentials.get({
  mediation: "conditional",
  identity: {
    providers: [{
      configURL: "https://fedcm-demo-idp.dev/fedcm.json",
      clientId: "https://fedcm-demo-rp.dev",
      params: {
        nonce,
      },
    }]
  },
});
              
            

Read the full explainer at the w3c-fedid/FedCM issue #694 repository.