---
title: "Initializes passkey authentication for the user(s) corresponding to the identifier provided."
method: POST
path: "/v1/passkey/start-authentication-by-user"
tags: ["Accounts"]
---

# Initializes passkey authentication for the user(s) corresponding to the identifier provided.

`POST /v1/passkey/start-authentication-by-user`

## Request body

- RobloxAuthenticationApiModelsRequestStartAuthenticationByUserRequest
  - `ctype` 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10, required
  - `cvalue` string, required

## Response `200`

OK

- RobloxAuthenticationApiModelsResponseStartAuthenticationByUserResponse
  - `authenticationOptions` string
  - `sessionId` string

## Other responses

- `400` — 5: User identifier and type are required. 6: Multi-user passkey authentication is not supported for this credential type.
- `403` — 0: Token Validation Failed 4: No passkeys registered for any users found.
- `503` — 2: Feature disabled.

## Changes

- **2026-09-03** `d9b4ae8b3380` — 1 info
  - endpoint added

[Change history](https://skmtc.dev/roblox/apis/roblox-api/changes/v1/passkey/start-authentication-by-user/post.md)

---

[API](https://skmtc.dev/roblox/apis/roblox-api.md) · [All operations](https://skmtc.dev/roblox/apis/roblox-api/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/roblox/roblox-api/revisions/d9b4ae8b3380/schema)