# First-party passwordless login (/docs/auth/flows/first-party-passwordless)



The first-party passwordless flow sends an OTP to the user's verified email
address or phone number, then resumes the authorization challenge with the OTP to
obtain an authorization code.

<SalesforceReference title="Headless Passwordless Login for Private Clients" href="https://help.salesforce.com/s/articleView?id=remoteaccess_auth_challenge_passwordless_login.htm&language=en_US&type=5" />

## Initialize passwordless login [#initialize-passwordless-login]

```ts
import { SalesforceAuth } from "@kysoql/auth";

export function beginPasswordless(
  username: string,
  clientAssertion: string,
  codeChallenge: string,
) {
  const auth = new SalesforceAuth({
    loginUrl: "https://customers.example.my.site.com/customers",
    clientId: "external-client-app-id",
  });

  return auth.firstPartyAuthorizationChallenge({
    parameters: {
      username,
      login_type: "email",
      client_assertion: clientAssertion,
      client_id: "external-client-app-id",
      code_challenge: codeChallenge,
      scope: "api refresh_token",
    },
  });
}
```

A successful initialization is still a challenge response: Salesforce returns an
`auth_session` and a login state indicating that the OTP was sent.

## Submit the OTP [#submit-the-otp]

```ts
import { SalesforceAuth } from "@kysoql/auth";

export function submitPasswordlessOtp(authSession: string, otp: string) {
  const auth = new SalesforceAuth({
    loginUrl: "https://customers.example.my.site.com/customers",
    clientId: "external-client-app-id",
  });

  return auth.firstPartyAuthorizationChallenge({
    parameters: {
      auth_session: authSession,
      login_otp: otp,
    },
  });
}
```

When Salesforce returns `kind: "authorized"`, exchange the authorization code
through [`auth.exchangeAuthorizationCode()`](/docs/auth/flows/web-server-pkce) using the
matching PKCE verifier.

For identifier-based discovery instead of a Salesforce username, follow
Salesforce's `login_hint`/`customdata` requirements for this flow.