---
title: "Start OAuth2 web flow"
method: GET
path: "/oauth2/auth"
tags: ["OAuth2"]
---

# Start OAuth2 web flow

`GET /oauth2/auth`

## Request

- Base URL: `https://oauth2.mercury.com`
- URL: `https://oauth2.mercury.com/oauth2/auth`
- Auth: none declared

Initiates the OAuth2 authorization flow. Redirects the user to Mercury's consent page.

## Query parameters

- `client_id` string, required
- `redirect_uri` string, required
- `scope` string, required
- `state` string
- `response_type` string, required
- `code_challenge` string
- `code_challenge_method` string

## Other responses

- `302`
- `400`: Invalid `code_challenge_method` or `code_challenge` or `response_type` or `state` or `scope` or `redirect_uri` or `client_id`

---

[API](https://skmtc.dev/mercurytechnologies/apis/mercury-oauth2-api.md) - [All operations](https://skmtc.dev/mercurytechnologies/apis/mercury-oauth2-api/llms.txt) - [OpenAPI document](https://skmtc.dev/mercurytechnologies/apis/mercury-oauth2-api/revisions/e870b77c0891?raw)