> ## Documentation Index > Fetch the complete documentation index at: https://docs.qumo-deploy.com/llms.txt > Use this file to discover all available pages before exploring further. # Start a plan checkout > Opens an embedded Stripe Checkout session that subscribes the organization to Pay as you go, billed in arrears for relay egress, and returns the client secret to mount it with Stripe's Payment Element. An organization that already has a live subscription is refused with 409. ## OpenAPI ````yaml /api-reference/openapi.yaml post /v1/billing/checkout-sessions openapi: 3.1.0 info: title: Qumo Deploy REST API description: > The Qumo Deploy control plane: organizations, projects, signing keys, machine identities, access control, audit and billing. Relay credentials are not issued here: your app signs them with its own [signing keys](/guides/signing-keys). Every operation here is generated against the routes the server registers and checked in CI, so an operation in this reference exists and a route missing from it is deliberately internal (relay mesh, webhooks, probes, operator-only and browser sign-in routes). Errors are JSON objects with one `error` field. What each status code means is in [Error codes](/guides/error-codes); the token scope each permission needs is in [Scopes and permissions](/guides/scopes-permissions). version: 1.0.0 servers: - url: https://api.qumo-deploy.com description: Public API (Bearer tokens only; cookies are ignored) security: [] tags: - name: Account description: The signed-in user's own sessions, tokens, security settings and data. - name: Device flow description: OAuth 2.0 device authorization, used by `qumod login`. - name: Organizations description: Organizations, their members and usage. - name: Projects description: Projects inside an organization. - name: Signing keys description: Keys your app signs relay credentials with. - name: Relays description: Where clients of a broadcast path connect. - name: Identities description: Machine identities, their tokens and IP allowlists. - name: Access control description: Roles, IAM bindings and invitations. - name: Audit description: The audit log and its webhook. - name: Notifications description: Notification policies. - name: Billing description: Plans, usage cost, budgets, invoices and payment methods. - name: Pricing description: Public price list. paths: /v1/billing/checkout-sessions: post: tags: - Billing summary: Start a plan checkout description: > Opens an embedded Stripe Checkout session that subscribes the organization to Pay as you go, billed in arrears for relay egress, and returns the client secret to mount it with Stripe's Payment Element. An organization that already has a live subscription is refused with 409. operationId: createCheckoutSession parameters: - $ref: '#/components/parameters/OrganizationIdQuery' requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/CheckoutSessionRequest' responses: '200': description: The checkout session was created. content: application/json: schema: $ref: '#/components/schemas/CheckoutSession' '400': $ref: '#/components/responses/BadRequest' '401': $ref: '#/components/responses/Unauthorized' '403': $ref: '#/components/responses/Forbidden' '409': $ref: '#/components/responses/Conflict' '429': $ref: '#/components/responses/TooManyRequests' security: - token: [] - cliSession: [] - sessionCookie: [] csrfToken: [] components: parameters: OrganizationIdQuery: name: organization_id in: query required: false description: > The organization the request acts in. Required with a personal token or a session, which name no organization themselves; an identity token's organization is implied. schema: type: string format: uuid example: 3f8c2a1e-7b4d-4e9a-9c61-2d5e8f0a1b7c schemas: CheckoutSessionRequest: type: object properties: plan_name: type: string enum: - Pay as you go default: Pay as you go description: >- The plan to subscribe to. Pay as you go is the only plan sold at checkout, and the default. example: Pay as you go CheckoutSession: type: object required: - client_secret - publishable_key properties: client_secret: type: string description: >- The Checkout Session's client secret, for mounting Stripe's Payment Element. example: cs_live_a1B2c3D4e5F6g7H8_secret_9iJ0kL1mN2oP3qR4 publishable_key: type: string description: The Stripe publishable key to initialise Stripe.js with. example: pk_live_51QxR7aLkdIwHu7ixAbCdEfGhIjKlMnOp Error: type: object required: - error properties: error: type: string description: A human-readable message. example: organization_id is required responses: BadRequest: description: >- Malformed request or failed validation. See [Error codes](/guides/error-codes). content: application/json: schema: $ref: '#/components/schemas/Error' Unauthorized: description: Missing or invalid credentials. See [Error codes](/guides/error-codes). content: application/json: schema: $ref: '#/components/schemas/Error' Forbidden: description: >- Authenticated but not allowed (permission, token scope, IP allowlist or CSRF). See [Error codes](/guides/error-codes). content: application/json: schema: $ref: '#/components/schemas/Error' Conflict: description: >- Conflicts with the current state. See [Error codes](/guides/error-codes). content: application/json: schema: $ref: '#/components/schemas/Error' TooManyRequests: description: >- Rate limited; retry with backoff. See [Error codes](/guides/error-codes). content: application/json: schema: $ref: '#/components/schemas/Error' securitySchemes: token: type: http scheme: bearer bearerFormat: qumo_pat_ description: > A personal access token (`POST /v1/auth/tokens`) or a machine identity token (`POST /v1/projects/{project_id}/identities/{identity_id}/tokens`), both prefixed `qumo_pat_`. A token's scopes cap what it can do; see [Scopes and permissions](/guides/scopes-permissions). A personal token names no organization: on a route whose path names no project or organization, pass `?organization_id=`. cliSession: type: http scheme: bearer description: | The session token `qumod login` obtains through the device flow (`POST /v1/auth/device/token`). It acts as the signed-in user, like a console session, and needs no CSRF token. sessionCookie: type: apiKey in: cookie name: __Host-qumo_session description: | The console's browser session. Accepted only on the console origin (`https://console.qumo-deploy.com`), never on `api.qumo-deploy.com`. A request that changes state must also send `X-CSRF-Token`. csrfToken: type: apiKey in: header name: X-CSRF-Token description: | CSRF token paired with `sessionCookie` on POST, PUT, PATCH and DELETE. Bearer requests do not send it. ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.