---
title: "Start (or upgrade to) the paid managed plan — returns a hosted Stripe Checkout link."
method: POST
path: "/checkout"
tags: ["account"]
---

# Start (or upgrade to) the paid managed plan — returns a hosted Stripe Checkout link.

`POST /checkout`

## Request

- Base URL: `https://api.coldrig.dev`
- URL: `https://api.coldrig.dev/checkout`
- Auth: HTTP bearer

Subscribes the account to the single `managed` plan: $49 a month covers the first 3 mailboxes and each extra mailbox is $5 a month (3-mailbox / $49 minimum; no setup fee, no domain fee; an account already paying keeps its own minimum and price). `mailboxes` (3 or more) seeds the initial quote only — the billed quantity then TRACKS the account's live set-up mailbox count, never a commitment for mailboxes not yet set up. Returns a hosted Stripe Checkout URL to open and pay. `mode` is `"simulated"` only in a fully-unarmed test environment where no real purchase is possible; `"stripe"` once real billing is armed.

## Request body

- object
  - `mailboxes` integer, required: Initial committed mailbox count (3 or more).
  - `interval` 'month' | 'year'

## Response `201`

Hosted checkout session created.

- CheckoutResult: `mode` is `"simulated"` only when this environment cannot reach real vendor billing at all (no Stripe key wired, no engine armed) — a fully-unarmed test environment; otherwise `"stripe"`. `url` is the hosted Checkout link to open and pay. `sessionId` identifies the checkout session; it is re-validated account-scoped server-side on the return leg, never trusted as a bare credential. `forAgents` is plain-language guidance for the calling agent on how to complete this checkout (pay via a Stripe Link agent wallet, or hand the URL to a human); its wording varies by `mode`.
  - `mode` 'stripe' | 'simulated', required
  - `url` string, uri, required
  - `sessionId` string, required
  - `forAgents` string, required

## Other responses

- `400`: Request body failed schema validation.
- `401`: Missing, invalid, or inactive bearer token.

---

[API](https://skmtc.dev/coldrig/apis/agent-cold-email-api.md) · [All operations](https://skmtc.dev/coldrig/apis/agent-cold-email-api/llms.txt) · [OpenAPI document](https://skmtc.dev/coldrig/apis/agent-cold-email-api/revisions/242a462d82c4?raw)