---
title: "Start a hosted Square checkout for a paid tier"
method: POST
path: "/v1/checkout"
---

# Start a hosted Square checkout for a paid tier

`POST /v1/checkout`

## Request

- Base URL: `https://agentmandate-api.com`
- URL: `https://agentmandate-api.com/v1/checkout`
- Auth: none required

Returns a Square-hosted payment URL for the requested tier. No API key is needed — a prospect has not got one yet. The email Square collects becomes the account, so a key issued later for the same address inherits the paid quota. Enterprise returns a contact route rather than a payment link. THIS IS THE PATH FOR SOMEONE WHO IS NOT YET PAYING. It starts a NEW Square recurring subscription, so it is refused with 409 `conflict` (`details.reason` `existing_subscription`) when the request carries a dashboard session for an account that already has a live plan on this API — a second subscription would be charged alongside the first, every month, and this API cannot cancel either one. Change tier with POST /v1/subscription/plan, or, when Square collects your base fee, cancel it with Square first.

## Request body

- object
  - `tier` string, required: developer | growth | scale | enterprise

## Response `200`

Success

- object
  - `checkoutUrl` string, uri: Square-hosted payment page. Redirect the buyer here.
  - `tier` string
  - `sku` string
  - `requestId` string

## Other responses

- `400`: Deterministic error. Branch on `code`; quote `requestId` when reporting a problem.
- `409`: Deterministic error. Branch on `code`; quote `requestId` when reporting a problem.
- `500`: Deterministic error. Branch on `code`; quote `requestId` when reporting a problem.

---

[API](https://skmtc.dev/agentmandate-api/apis/agent-mandate.md) · [All operations](https://skmtc.dev/agentmandate-api/apis/agent-mandate/llms.txt) · [OpenAPI document](https://skmtc.dev/agentmandate-api/apis/agent-mandate/revisions/463fe122c4d8?raw)