Join free membership after verified sign-in

POST /v1/developer/guest/me/membership

Operation ID: joinDeveloperGuestMembership

Requires server-only guest_preferences.write, verified guest proof, CSRF, registered parentOrigin, current displayed membership terms and a stable idempotency key. Joins the installed collection using canonical membership and consent authorities. Preserves email-marketing preference and sends no email. Replays return current state without reactivating a later cancellation. TEST stores an isolated rehearsal only. Paid memberships are unsupported.

Contract status

Field	Value
Maturity	`preview`
Required capability	`guest_preferences.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-guest-token`	header	string	yes	Verified guest access token held by your same-origin BFF, never browser JavaScript.
`x-kismet-csrf`	header	string	yes

Request body

The request body is JSON. The canonical schema is:

{
  "type": "object",
  "properties": {
    "accepted": {
      "type": "boolean",
      "enum": [
        true
      ]
    },
    "expectedGuestId": {
      "type": "string",
      "minLength": 1,
      "maxLength": 128
    },
    "disclosureVersion": {
      "type": "string",
      "minLength": 1,
      "maxLength": 40
    },
    "disclosureHash": {
      "type": "string",
      "pattern": "^[a-f0-9]{64}$"
    },
    "idempotencyKey": {
      "type": "string",
      "minLength": 16,
      "maxLength": 100,
      "pattern": "^[A-Za-z0-9_-]+$"
    },
    "parentOrigin": {
      "type": "string",
      "format": "uri"
    }
  },
  "required": [
    "accepted",
    "expectedGuestId",
    "disclosureVersion",
    "disclosureHash",
    "idempotencyKey",
    "parentOrigin"
  ],
  "additionalProperties": false
}

Minimal example:

{
  "accepted": true,
  "expectedGuestId": "string",
  "disclosureVersion": "string",
  "disclosureHash": "string",
  "idempotencyKey": "string",
  "parentOrigin": "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/me/membership" \
  --header "Authorization: Bearer $KISMET_DEVELOPER_API_KEY" \
  --header "Accept: application/json" \
  --header "x-kismet-guest-token: $GUEST_ACCESS_TOKEN" \
  --header "x-kismet-csrf: $VALIDATED_CSRF_TOKEN" \
  --header "Content-Type: application/json" \
  --data '{"accepted":true,"expectedGuestId":"string","disclosureVersion":"string","disclosureHash":"string","idempotencyKey":"string","parentOrigin":"string"}'

Responses

Status	Meaning
200	Success.
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.
404	The authorized resource was not found.
409	Request conflicts with the installation environment or current state.
429	Rate limit or quota exceeded; inspect response metadata before retrying.
503	A required Kismet dependency is temporarily unavailable.

200 response schema

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

View complete response schema

{
  "type": "object",
  "additionalProperties": false,
  "required": [
    "receiptId",
    "environment",
    "membership",
    "replayed"
  ],
  "properties": {
    "receiptId": {
      "type": "string",
      "format": "uuid"
    },
    "environment": {
      "type": "string",
      "enum": [
        "TEST",
        "LIVE"
      ]
    },
    "membership": {
      "type": "object",
      "additionalProperties": false,
      "required": [
        "status",
        "joinedAt"
      ],
      "properties": {
        "status": {
          "type": "string",
          "enum": [
            "NOT_JOINED",
            "ACTIVE"
          ]
        },
        "joinedAt": {
          "type": [
            "null",
            "string"
          ],
          "format": "date-time"
        }
      }
    },
    "replayed": {
      "type": "boolean"
    }
  }
}