---
title: "Begin usernameless passkey sign-in"
method: POST
path: "/api/auth/passkey/start"
tags: ["Authentication"]
---

# Begin usernameless passkey sign-in

`POST /api/auth/passkey/start`

## Request

- Base URL: `https://slimlytics.com`
- URL: `https://slimlytics.com/api/auth/passkey/start`
- Auth: none required

## Response `200`

WebAuthn request options

- WebAuthnChallenge
  - `challengeId` string, uuid, required: Single-use ceremony ID; expires after 5 minutes
  - `options` object, required: WebAuthn `publicKey` creation or request options (binary fields are base64url)

## Other responses

- `400`: Invalid request
- `401`: Authentication required
- `429`: Too many sign-in attempts from this address
- `500`: Internal service error

---

[API](https://skmtc.dev/slimlytics/apis/slimlytics-api.md) · [All operations](https://skmtc.dev/slimlytics/apis/slimlytics-api/llms.txt) · [OpenAPI document](https://skmtc.dev/slimlytics/apis/slimlytics-api/revisions/f9a26641a254?raw)