---
title: "POST /agent-commerce/ucp/checkout-sessions"
method: POST
path: "/agent-commerce/ucp/checkout-sessions"
---

# POST /agent-commerce/ucp/checkout-sessions

`POST /agent-commerce/ucp/checkout-sessions`

## Request

- Base URL: `https://mondoir.art`
- URL: `https://mondoir.art/agent-commerce/ucp/checkout-sessions`
- Auth: HTTP bearer
- TypeScript: <https://skmtc.dev/mondoir/apis/mondoir-api/docs/agent-commerce/ucp/checkout-sessions/post.ts> (a function with typed inputs; its response is checked against the schema)

Create a one-item progressive checkout. Read the payment handler specification.

## Request body

- object
  - `buyer` object
    - `email` string, email
    - `first_name` string
    - `last_name` string
    - `full_name` string
    - `phone_number` string
  - `currency` 'USD', required
  - `id` string, uuid
  - `line_items` object[], required
    - `id` 'line-1'
    - `item` object, required
      - `id` string, required
    - `quantity` integer, required
  - `fulfillment` object
    - `methods` object[], required
      - `id` 'shipping'
      - `type` 'shipping'
      - `line_item_ids` string[]
      - `destinations` object[]
        - `id` string
        - `street_address` string
        - `extended_address` string
        - `address_locality` string
        - `address_region` string
        - `address_country` string
        - `postal_code` string
        - `first_name` string
        - `last_name` string
        - `full_name` string
        - `phone_number` string
      - `selected_destination_id` string, nullable
  - `mondoir` object
    - `payer` union
      - string
      - string
    - `network` 'eip155:8453' | 'eip155:137' | 'eip155:42161' | 'eip155:480' | 'eip155:143' | 'solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp'
    - `quantity` integer
    - `variantId` string
    - `editionNumber` integer
    - `editionNumbers` integer[]
    - `walletAddress` string

## Response `201`

Created checkout.

## Changes

- **2026-11-09** `5c50dd5066f8`: 2 breaking, 2 warning
  - added the pattern `^(?:[A-Za-z0-9_'+\-]+\.)*[A-Za-z0-9_'+\-]*[A-Za-z0-9_+-]@(?:[A-Za-z0-9][A-Za-z0-9\-]*\.)+[A-Za-z]{2,}$` to the request property `buyer/email`
  - added the pattern `^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000|ffffffff-ffff-ffff-ffff-ffffffffffff)$` to the request property `id`
  - the `mondoir/editionNumber` request property's max was set to `9007199254740991.00`
  - the `mondoir/editionNumbers/items/` request property's max was set to `9007199254740991.00`
- **2026-10-19** `8a0a695bcfb5`: 1 breaking, 3 info
  - the `mondoir/payer` request property type changed from `string` to no type
  - added the new optional request property `mondoir/network`
  - added `subschema #1, subschema #2` to the `mondoir/payer` request property `anyOf` list
  - removed the pattern `^0x[0-9a-fA-F]{40}$` from the request property `mondoir/payer`
- **2026-10-18** `4990dc8b3ef4`: 1 info
  - endpoint added

[Operation history](https://skmtc.dev/mondoir/apis/mondoir-api/changes/agent-commerce/ucp/checkout-sessions/post.md)

---

[API](https://skmtc.dev/mondoir/apis/mondoir-api.md) - [All operations](https://skmtc.dev/mondoir/apis/mondoir-api/llms.txt) - [OpenAPI document](https://skmtc.dev/mondoir/apis/mondoir-api/revisions/5c50dd5066f8?raw)