---
title: "Finish a business sign-in"
method: POST
path: "/identity/sign_in/step_3"
tags: ["identity", "customer-session", "customer-session-public"]
---

# Finish a business sign-in

`POST /identity/sign_in/step_3`

## Request

- Base URL: `https://api.stablesea.com` (the document declares no server; this is the origin it was published from)
- URL: `https://api.stablesea.com/identity/sign_in/step_3`
- Auth: none declared

Select a business returned by second-factor verification using its short-lived session_token. Installs HttpOnly access and refresh cookies on the requested host. Keep the complete cookie jar for subsequent requests; no API key is used.

## Request body

- AuthSignInStep3Input
  - `group_id` string, required
  - `session_token` string, required

## Response `200`

OK

- AuthSignInStep3Output
  - `success` boolean

## Other responses

- `400`: Bad Request
- `401`: Unauthorized
- `403`: Forbidden
- `409`: Conflict
- `429`: Too Many Requests
- `500`: Internal Server Error
- `503`: Service Unavailable

## Changes

- **2026-10-29** `e003c8a67b62`: 7 info
  - added the optional property `error/authorization` to the response with the `400` status
  - added the optional property `error/authorization` to the response with the `401` status
  - added the optional property `error/authorization` to the response with the `403` status
  - added the optional property `error/authorization` to the response with the `409` status
  - …3 more
- **2026-10-15** `33870379032d`: 1 info
  - endpoint added

[Operation history](https://skmtc.dev/stablesea/apis/stable-sea-backend/changes/identity/sign_in/step_3/post.md)

---

[API](https://skmtc.dev/stablesea/apis/stable-sea-backend.md) - [All operations](https://skmtc.dev/stablesea/apis/stable-sea-backend/llms.txt) - [OpenAPI document](https://skmtc.dev/stablesea/apis/stable-sea-backend/revisions/772c80d83658?raw)