curl -X POST \
"https://www.gomry.com/api/v1/checkout_sessions/acp_sess_AbCdEfGhIjKlMnOpQrSt" \
-H "X-API-KEY: your_api_key" \
-H "Content-Type: application/json" \
-H "API-Version: 2025-09-12" \
-H "Timestamp: 2026-09-10T12:01:00Z" \
-H "Signature: base64-hmac-sha256" \
-d '{ "buyer": { "name": "Ada Lovelace", "email": "ada@example.com" } }'
const body = JSON.stringify({
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/${sessionId}`,
{
method: "POST",
headers: {
"X-API-KEY": process.env.GOMRY_API_KEY,
"Content-Type": "application/json",
"API-Version": "2025-09-12",
Timestamp: timestamp,
Signature: signature,
},
body,
}
);
{
"id": "acp_sess_AbCdEfGhIjKlMnOpQrSt",
"buyer": { "name": "Ada Lovelace", "email": "ada@example.com" },
"status": "ready_for_payment",
"currency": "usd",
"line_items": [
{
"id": "li_1",
"item": { "id": "TktAbCdEfGhIjKlMnOpQ", "quantity": 2 },
"base_amount": 15800,
"discount": 0,
"subtotal": 15800,
"tax": 0,
"total": 16790
}
],
"totals": [
{ "type": "items_base_amount", "display_text": "Tickets", "amount": 15800 },
{ "type": "fee", "display_text": "Service fee", "amount": 990 },
{ "type": "total", "display_text": "Total", "amount": 16790 }
],
"messages": []
}
Checkout Sessions
Update Checkout Session
Patch the cart, buyer, or answers on an open session
POST
/
checkout_sessions
/
{checkout_session_id}
curl -X POST \
"https://www.gomry.com/api/v1/checkout_sessions/acp_sess_AbCdEfGhIjKlMnOpQrSt" \
-H "X-API-KEY: your_api_key" \
-H "Content-Type: application/json" \
-H "API-Version: 2025-09-12" \
-H "Timestamp: 2026-09-10T12:01:00Z" \
-H "Signature: base64-hmac-sha256" \
-d '{ "buyer": { "name": "Ada Lovelace", "email": "ada@example.com" } }'
const body = JSON.stringify({
buyer: { name: "Ada Lovelace", email: "ada@example.com" },
});
const timestamp = new Date().toISOString();
const signature = crypto
.createHmac("sha256", process.env.GOMRY_ACP_SIGNING_SECRET)
.update(`${timestamp}.${body}`)
.digest("base64");
const res = await fetch(
`https://www.gomry.com/api/v1/checkout_sessions/${sessionId}`,
{
method: "POST",
headers: {
"X-API-KEY": process.env.GOMRY_API_KEY,
"Content-Type": "application/json",
"API-Version": "2025-09-12",
Timestamp: timestamp,
Signature: signature,
},
body,
}
);
{
"id": "acp_sess_AbCdEfGhIjKlMnOpQrSt",
"buyer": { "name": "Ada Lovelace", "email": "ada@example.com" },
"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
}
],
"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": []
}
Update Checkout Session
Patches an open session and returns it re-priced. This is how you clear blockingmessages[] and move a session to ready_for_payment.
Requires
checkout: write, an allowlisted partner key, and a signed request — same headers as create.POST, not PATCH, for updates.
Path Parameters
string
required
The session to update.
Body
Every field is optional — send only what changes.array
1–20 lines. Replaces the cart wholesale, it is not merged. To change one line, send all the lines you want.
object
name and email required when present. Commonly used to supply the buyer after creating a session without one.array
Up to 50 answers. Replaces the stored set wholesale, like
items.object
Required before payment when the cart contains a posted ticket.
string
The chosen option’s id.
items and attendee_answers replace, they do not merge. Sending items: [{id: "A", quantity: 1}] on a session that held A and B removes B.Response
200 with the re-priced session.
Totals are recalculated on every update, so a price change or a tier selling out shows up here rather than surprising you at completion.
Terminal sessions cannot be updated
Acompleted or canceled session is immutable and returns 409 invalid_session_state.
A completed session is immutable because editing the cart behind a paid order would make the stored session disagree with what the buyer was actually charged for and what their tickets say.
Working through blockers
Clearing blocking messages
let session = await createSession(items);
while (session.status === "not_ready_for_payment") {
const blockers = session.messages.filter((m) => m.type === "error");
if (!blockers.length) break; // not payable, but nothing actionable
const patch = {};
for (const m of blockers) {
if (m.param === "buyer.name") patch.buyer = await askBuyer();
if (m.param?.startsWith("attendee_answers")) {
patch.attendee_answers = await askQuestions();
}
if (m.code === "out_of_stock") return handleSoldOut(m);
}
if (!Object.keys(patch).length) return giveUp(blockers);
session = await updateSession(session.id, patch);
}
curl -X POST \
"https://www.gomry.com/api/v1/checkout_sessions/acp_sess_AbCdEfGhIjKlMnOpQrSt" \
-H "X-API-KEY: your_api_key" \
-H "Content-Type: application/json" \
-H "API-Version: 2025-09-12" \
-H "Timestamp: 2026-09-10T12:01:00Z" \
-H "Signature: base64-hmac-sha256" \
-d '{ "buyer": { "name": "Ada Lovelace", "email": "ada@example.com" } }'
const body = JSON.stringify({
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/${sessionId}`,
{
method: "POST",
headers: {
"X-API-KEY": process.env.GOMRY_API_KEY,
"Content-Type": "application/json",
"API-Version": "2025-09-12",
Timestamp: timestamp,
Signature: signature,
},
body,
}
);
{
"id": "acp_sess_AbCdEfGhIjKlMnOpQrSt",
"buyer": { "name": "Ada Lovelace", "email": "ada@example.com" },
"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
}
],
"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": []
}