Start hosted Google guest sign-in

POST /v1/developer/guest-auth/google/authorizations

Operation ID: startDeveloperGuestGoogleAuthorization

Starts Google sign-in using Kismet’s registered callback. Requires a server credential with guest_auth.write, an exact authorized HTTPS Origin and a same-origin BFF CSRF proof. The BFF supplies S256 PKCE and state; returnPath stays on that origin. No guest session or marketing consent is created. TEST requires a registered test identity unless an unexpired, manager-enabled real-Google staging participation policy covers this exact verified staging origin.

Contract status

Field	Value
Maturity	`preview`
Required capability	`guest_auth.write`
Freshness class	`authenticated-state`
Quota cost	`1`

All operations require a Kismet Developer Bearer credential. Collection and resource authority is resolved from the credential’s installation grants; identifiers in the URL never grant access.

Request parameters

Name	In	Type	Required	Description
`x-kismet-csrf`	header	string	yes
`origin`	header	string	yes

Request body

The request body is JSON. The canonical schema is:

{
  "type": "object",
  "additionalProperties": false,
  "required": [
    "returnPath",
    "kidSid",
    "state",
    "codeChallenge"
  ],
  "properties": {
    "returnPath": {
      "type": "string",
      "maxLength": 2048
    },
    "kidSid": {
      "type": "string",
      "pattern": "^kid_[A-Za-z0-9]{8}$"
    },
    "state": {
      "type": "string",
      "pattern": "^[a-zA-Z0-9_-]{43}$"
    },
    "codeChallenge": {
      "type": "string",
      "pattern": "^[a-zA-Z0-9_-]{43}$"
    }
  }
}

Minimal example:

{
  "returnPath": "string",
  "kidSid": "kid_Ab12Cd34",
  "state": "string",
  "codeChallenge": "string"
}

cURL

Set KISMET_API_ORIGIN=https://api.ksmt.app and configure KISMET_DEVELOPER_API_KEY in your environment. Run server-credential requests from your backend, not browser code.

Guest access tokens come from the signed-in guest session held by your backend. Forward a CSRF proof only after your same-origin backend validates it. If shown, KISMET_SITE_ORIGIN is the authorized origin of your site. Do not substitute a guest ID or an invented token.

curl --request POST \
  "$KISMET_API_ORIGIN/v1/developer/guest-auth/google/authorizations" \
  --header "Authorization: Bearer $KISMET_DEVELOPER_API_KEY" \
  --header "Accept: application/json" \
  --header "x-kismet-csrf: $VALIDATED_CSRF_TOKEN" \
  --header "origin: $KISMET_SITE_ORIGIN" \
  --header "Content-Type: application/json" \
  --data '{"returnPath":"string","kidSid":"kid_Ab12Cd34","state":"string","codeChallenge":"string"}'

Responses

Status	Meaning
201	Created successfully.
400	Invalid request parameters or body.
401	Missing, invalid, expired, or inappropriate credential/session.
403	Credential lacks the required grant/capability, or an origin/CSRF check failed.
409	Request conflicts with the installation environment or current state.
410	The single-use authentication challenge is no longer valid.
429	Rate limit or quota exceeded; inspect response metadata before retrying.
503	A required Kismet dependency is temporarily unavailable.

201 response example

{
  "authorizationUrl": "https://accounts.google.com/o/oauth2/v2/auth?client_id=example&response_type=code",
  "expiresAt": "2026-09-27T18:10:00.000Z"
}

201 response schema

Content type: application/json. Required fields, nullable values, and nested structures are defined below.

View complete response schema

{
  "type": "object",
  "required": [
    "authorizationUrl",
    "expiresAt"
  ],
  "properties": {
    "authorizationUrl": {
      "type": "string",
      "format": "uri"
    },
    "expiresAt": {
      "type": "string",
      "format": "date-time"
    }
  }
}