curl -X POST "https://www.gomry.com/api/v1/checkout_sessions" \
  -H "X-API-KEY: your_api_key" \
  -H "Content-Type: application/json" \
  -H "API-Version: 2025-09-12" \
  -H "Timestamp: 2026-09-10T12:00:00Z" \
  -H "Signature: base64-hmac-sha256" \
  -H "Idempotency-Key: 8f14e45f-ea0c-4b9f-9c2a-1d3e5f7a9b0c" \
  -d '{
    "items": [{ "id": "TktAbCdEfGhIjKlMnOpQ", "quantity": 2 }],
    "buyer": { "name": "Ada Lovelace", "email": "ada@example.com" },
    "attendee_answers": [
      { "question_id": "QstAbCdEfGhIjKlMnOpQ", "value": "Vegetarian" }
    ]
  }'

import crypto from "crypto";

const body = JSON.stringify({
  items: [{ id: "TktAbCdEfGhIjKlMnOpQ", quantity: 2 }],
  buyer: { name: "Ada Lovelace", email: "ada@example.com" },
});
const timestamp = new Date().toISOString();
const signature = crypto
  .createHmac("sha256", process.env.GOMRY_ACP_SIGNING_SECRET)
  .update(`${timestamp}.${body}`)
  .digest("base64");

const res = await fetch("https://www.gomry.com/api/v1/checkout_sessions", {
  method: "POST",
  headers: {
    "X-API-KEY": process.env.GOMRY_API_KEY,
    "Content-Type": "application/json",
    "API-Version": "2025-09-12",
    Timestamp: timestamp,
    Signature: signature,
    "Idempotency-Key": crypto.randomUUID(),
  },
  body, // the exact string that was signed
});
const session = await res.json();

{
  "id": "acp_sess_AbCdEfGhIjKlMnOpQrSt",
  "buyer": { "name": "Ada Lovelace", "email": "ada@example.com" },
  "payment_provider": {
    "provider": "stripe",
    "supported_payment_methods": ["card"]
  },
  "status": "ready_for_payment",
  "currency": "usd",
  "line_items": [
    {
      "id": "li_1",
      "item": { "id": "TktAbCdEfGhIjKlMnOpQ", "quantity": 2 },
      "base_amount": 15800,
      "discount": 0,
      "subtotal": 15800,
      "tax": 0,
      "total": 16790
    }
  ],
  "fulfillment_address": null,
  "fulfillment_option_id": "digital",
  "fulfillment_options": [
    {
      "type": "digital",
      "id": "digital",
      "title": "Digital ticket",
      "subtitle": "Delivered by email",
      "subtotal": 0,
      "tax": 0,
      "total": 0
    }
  ],
  "totals": [
    { "type": "items_base_amount", "display_text": "Tickets", "amount": 15800 },
    { "type": "fee", "display_text": "Service fee", "amount": 990 },
    { "type": "total", "display_text": "Total", "amount": 16790 }
  ],
  "messages": [],
  "links": [
    { "type": "terms_of_use", "url": "https://www.gomry.com/terms" },
    { "type": "privacy_policy", "url": "https://www.gomry.com/privacy" }
  ]
}

{
  "id": "acp_sess_AbCdEfGhIjKlMnOpQrSt",
  "status": "not_ready_for_payment",
  "messages": [
    {
      "type": "error",
      "code": "missing",
      "param": "buyer.name",
      "content_type": "plain",
      "content": "A buyer name is required to issue a ticket."
    }
  ]
}

POST

checkout_sessions

curl -X POST "https://www.gomry.com/api/v1/checkout_sessions" \
  -H "X-API-KEY: your_api_key" \
  -H "Content-Type: application/json" \
  -H "API-Version: 2025-09-12" \
  -H "Timestamp: 2026-09-10T12:00:00Z" \
  -H "Signature: base64-hmac-sha256" \
  -H "Idempotency-Key: 8f14e45f-ea0c-4b9f-9c2a-1d3e5f7a9b0c" \
  -d '{
    "items": [{ "id": "TktAbCdEfGhIjKlMnOpQ", "quantity": 2 }],
    "buyer": { "name": "Ada Lovelace", "email": "ada@example.com" },
    "attendee_answers": [
      { "question_id": "QstAbCdEfGhIjKlMnOpQ", "value": "Vegetarian" }
    ]
  }'

import crypto from "crypto";

const body = JSON.stringify({
  items: [{ id: "TktAbCdEfGhIjKlMnOpQ", quantity: 2 }],
  buyer: { name: "Ada Lovelace", email: "ada@example.com" },
});
const timestamp = new Date().toISOString();
const signature = crypto
  .createHmac("sha256", process.env.GOMRY_ACP_SIGNING_SECRET)
  .update(`${timestamp}.${body}`)
  .digest("base64");

const res = await fetch("https://www.gomry.com/api/v1/checkout_sessions", {
  method: "POST",
  headers: {
    "X-API-KEY": process.env.GOMRY_API_KEY,
    "Content-Type": "application/json",
    "API-Version": "2025-09-12",
    Timestamp: timestamp,
    Signature: signature,
    "Idempotency-Key": crypto.randomUUID(),
  },
  body, // the exact string that was signed
});
const session = await res.json();

{
  "id": "acp_sess_AbCdEfGhIjKlMnOpQrSt",
  "buyer": { "name": "Ada Lovelace", "email": "ada@example.com" },
  "payment_provider": {
    "provider": "stripe",
    "supported_payment_methods": ["card"]
  },
  "status": "ready_for_payment",
  "currency": "usd",
  "line_items": [
    {
      "id": "li_1",
      "item": { "id": "TktAbCdEfGhIjKlMnOpQ", "quantity": 2 },
      "base_amount": 15800,
      "discount": 0,
      "subtotal": 15800,
      "tax": 0,
      "total": 16790
    }
  ],
  "fulfillment_address": null,
  "fulfillment_option_id": "digital",
  "fulfillment_options": [
    {
      "type": "digital",
      "id": "digital",
      "title": "Digital ticket",
      "subtitle": "Delivered by email",
      "subtotal": 0,
      "tax": 0,
      "total": 0
    }
  ],
  "totals": [
    { "type": "items_base_amount", "display_text": "Tickets", "amount": 15800 },
    { "type": "fee", "display_text": "Service fee", "amount": 990 },
    { "type": "total", "display_text": "Total", "amount": 16790 }
  ],
  "messages": [],
  "links": [
    { "type": "terms_of_use", "url": "https://www.gomry.com/terms" },
    { "type": "privacy_policy", "url": "https://www.gomry.com/privacy" }
  ]
}

{
  "id": "acp_sess_AbCdEfGhIjKlMnOpQrSt",
  "status": "not_ready_for_payment",
  "messages": [
    {
      "type": "error",
      "code": "missing",
      "param": "buyer.name",
      "content_type": "plain",
      "content": "A buyer name is required to issue a ticket."
    }
  ]
}

Create Checkout Session

Opens a checkout session and returns a priced cart.

Requires checkout: write, an allowlisted partner key, and a signed request. See Agentic Commerce.

Headers

string

2025-09-12. Always send it. A different value is refused with unsupported_api_version; an absent one is treated as the current version.

string

required

Base64 HMAC-SHA256 over {timestamp}.{raw_body}.

string

required

RFC 3339, within 5 minutes of our clock.

string

Recommended. Echoed back on the response.

Body

array

required

1–20 lines.

Show Item

string

required

A ticket type id from ticket_types[].id on the catalog detail endpoint. Not an event id.

integer

required

1–50, subject to the tier’s own max_per_order.

object

Show Buyer

string

required

Required by Gomry, though optional in the ACP spec. A ticket is admission for a named person: it prints the attendee’s name and the door list is read by a human. A nameless ticket is technically valid and useless at the door.

string

required

Where the ticket is delivered.

string

Optional.

The whole object may be omitted at create and supplied later with update — but the session will not reach ready_for_payment without it.

array

Up to 50 answers to the event’s registration questions. A Gomry extension to ACP: additive and optional, so a conforming client that never sends it still works — but an event with required questions reports them as blocking messages until they arrive.

Show Answer

string

required

From registration_questions[].id.

string

required

The answer as a string, whatever the question’s type. For dropdown and multipleChoice, must be one of the published options.

object

Accepted for spec conformance. ACP is shaped for physical goods; a ticket does not ship. Stored for the record, never used to fulfil — except for posted tickets, where it is required.

Unknown fields are rejected with 400 invalid_body, not ignored. A body carrying something like card_number must fail loudly rather than be quietly accepted into our logs. No field on this API ever carries a card number.

Response

201 with a checkout session. Read status first:

Status	What to do
`not_ready_for_payment`	Read `messages[]`, fix what is missing, then update the session.
`ready_for_payment`	Proceed to complete.

One session, one event

All items must belong to the same event and the same currency. Mixing them returns multiple_events or currency_mismatch. Sell two events as two sessions.

curl -X POST "https://www.gomry.com/api/v1/checkout_sessions" \
  -H "X-API-KEY: your_api_key" \
  -H "Content-Type: application/json" \
  -H "API-Version: 2025-09-12" \
  -H "Timestamp: 2026-09-10T12:00:00Z" \
  -H "Signature: base64-hmac-sha256" \
  -H "Idempotency-Key: 8f14e45f-ea0c-4b9f-9c2a-1d3e5f7a9b0c" \
  -d '{
    "items": [{ "id": "TktAbCdEfGhIjKlMnOpQ", "quantity": 2 }],
    "buyer": { "name": "Ada Lovelace", "email": "ada@example.com" },
    "attendee_answers": [
      { "question_id": "QstAbCdEfGhIjKlMnOpQ", "value": "Vegetarian" }
    ]
  }'

import crypto from "crypto";

const body = JSON.stringify({
  items: [{ id: "TktAbCdEfGhIjKlMnOpQ", quantity: 2 }],
  buyer: { name: "Ada Lovelace", email: "ada@example.com" },
});
const timestamp = new Date().toISOString();
const signature = crypto
  .createHmac("sha256", process.env.GOMRY_ACP_SIGNING_SECRET)
  .update(`${timestamp}.${body}`)
  .digest("base64");

const res = await fetch("https://www.gomry.com/api/v1/checkout_sessions", {
  method: "POST",
  headers: {
    "X-API-KEY": process.env.GOMRY_API_KEY,
    "Content-Type": "application/json",
    "API-Version": "2025-09-12",
    Timestamp: timestamp,
    Signature: signature,
    "Idempotency-Key": crypto.randomUUID(),
  },
  body, // the exact string that was signed
});
const session = await res.json();

{
  "id": "acp_sess_AbCdEfGhIjKlMnOpQrSt",
  "buyer": { "name": "Ada Lovelace", "email": "ada@example.com" },
  "payment_provider": {
    "provider": "stripe",
    "supported_payment_methods": ["card"]
  },
  "status": "ready_for_payment",
  "currency": "usd",
  "line_items": [
    {
      "id": "li_1",
      "item": { "id": "TktAbCdEfGhIjKlMnOpQ", "quantity": 2 },
      "base_amount": 15800,
      "discount": 0,
      "subtotal": 15800,
      "tax": 0,
      "total": 16790
    }
  ],
  "fulfillment_address": null,
  "fulfillment_option_id": "digital",
  "fulfillment_options": [
    {
      "type": "digital",
      "id": "digital",
      "title": "Digital ticket",
      "subtitle": "Delivered by email",
      "subtotal": 0,
      "tax": 0,
      "total": 0
    }
  ],
  "totals": [
    { "type": "items_base_amount", "display_text": "Tickets", "amount": 15800 },
    { "type": "fee", "display_text": "Service fee", "amount": 990 },
    { "type": "total", "display_text": "Total", "amount": 16790 }
  ],
  "messages": [],
  "links": [
    { "type": "terms_of_use", "url": "https://www.gomry.com/terms" },
    { "type": "privacy_policy", "url": "https://www.gomry.com/privacy" }
  ]
}

{
  "id": "acp_sess_AbCdEfGhIjKlMnOpQrSt",
  "status": "not_ready_for_payment",
  "messages": [
    {
      "type": "error",
      "code": "missing",
      "param": "buyer.name",
      "content_type": "plain",
      "content": "A buyer name is required to issue a ticket."
    }
  ]
}

Spaces

Events

Experiences

Recurrences

Attendees

Contacts

Ticket Classes

Forms

Applications

Custom Fields

Lists

Payments

Catalog

Checkout Sessions

Create Checkout Session

Create Checkout Session

Headers

Body

Response

One session, one event

​Create Checkout Session

​Headers

​Body

​Response

​One session, one event

Create Checkout Session

Headers

Body

Response

One session, one event