---
title: "Initiate SSO Authentication (Service Provider-Initiated Flow)"
method: POST
path: "/v2/authn/sso/{emailAddress}"
tags: ["SSO Authentication"]
---

# Initiate SSO Authentication (Service Provider-Initiated Flow)

`POST /v2/authn/sso/{emailAddress}`

## Request

- Base URL: `https://api.alianza.com`
- URL: `https://api.alianza.com/v2/authn/sso/{emailAddress}`
- Auth: API key in header `X-AUTH-TOKEN`
- TypeScript: <https://skmtc.dev/alianza/apis/alianza-public-api/docs/v2/authn/sso/:emailAddress/post.ts> (a function with typed inputs; its response is checked against the schema)

Initiates the SSO authentication process by redirecting the user to their configured Identity Provider (IdP).

What this endpoint does:
1. Looks up the SSO configuration based on the user's email domain
2. Generates a SAML authentication request
3. Returns the SAML request in a 200 or 303 response depending on request parameters

Note: This does not authenticate the user directly. It starts the redirect flow to the IdP.

## Path parameters

- `emailAddress` string, email, required

## Query parameters

- `redirect` boolean

## Headers

- `X-AUTH-REDIRECT-OVERRIDE` string, uri

## Response `200`

Redirect URI generated successfully

- RedirectResponse
  - `redirectUri` string, uri, required: URL of the Identity Provider login page where the user should be redirected

## Other responses

- `303`: See Other - redirect URL returned in the response body and optionally in the Location header.
- `400`: Bad Request - Invalid email or request parameters
- `404`: Not Found - SSO configuration not found for email domain
- `500`: Internal Server Error - Failed to build Auth0 URL

---

[API](https://skmtc.dev/alianza/apis/alianza-public-api.md) - [All operations](https://skmtc.dev/alianza/apis/alianza-public-api/llms.txt) - [OpenAPI document](https://skmtc.dev/alianza/apis/alianza-public-api/revisions/7223246c352c?raw)