> ## Documentation Index > Fetch the complete documentation index at: https://docs.meum.io/llms.txt > Use this file to discover all available pages before exploring further. # Create invoice > Creates a new checkout invoice for the authenticated store. Returns a legacy error shape on some validation failures for backward compatibility. ## OpenAPI ````yaml /openapi.yaml post /v1/invoices openapi: 3.1.0 info: title: Meum Public Merchant API version: 1.0.0 description: > Public merchant API for programmatic payment management: invoices, transactions, payment links, webhooks, and WooCommerce integration. Authenticate with a store-scoped API key (`sk_live_*`) via Bearer token. Base URL: https://api.meum.io contact: name: Meum Support email: support@meum.io url: https://meum.io servers: - url: https://api.meum.io description: Production security: - bearerAuth: [] tags: - name: Health description: Service health checks - name: Invoices description: Invoice lifecycle - name: Transactions description: On-chain payment transactions - name: Payment Links description: Reusable payment link management - name: Webhooks description: Webhook endpoint and delivery management - name: Integrations description: Third-party platform integrations paths: /v1/invoices: post: tags: - Invoices summary: Create invoice description: > Creates a new checkout invoice for the authenticated store. Returns a legacy error shape on some validation failures for backward compatibility. operationId: createInvoice requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/CreateInvoiceRequest' example: external_order_id: order_demo_1048 amount: '100.00' currency: USD return_url: https://shop.example.com/thank-you metadata: line_items: 2 responses: '201': description: Invoice created content: application/json: schema: $ref: '#/components/schemas/InvoiceCreateResponse' '400': description: Bad request (legacy error shape) content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '403': description: Forbidden (legacy error shape) content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '409': description: Conflict (legacy error shape) content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '429': description: Rate limited (legacy error shape) content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' components: schemas: CreateInvoiceRequest: type: object required: - external_order_id - amount properties: store_id: type: string format: uuid description: > Which store this invoice belongs to. **Optional**: uses your API key's default store if omitted. Must match the store tied to your API key when provided. integration_id: type: string format: uuid description: > **Optional.** Link this invoice to a connected platform (e.g. WooCommerce). Omit unless you received this ID from a platform integration. external_order_id: type: string description: > **Required.** Your own order or reference number (e.g. `"order_1048"`). Sent back in webhooks so you can match payments to orders in your system. example: order_demo_1048 amount: type: string description: > **Required.** How much you want to receive, as a decimal string (e.g. `"100.00"`). This is the amount after currency conversion, in the currency below. example: '100.00' currency: type: string default: USD description: > **Optional.** Three-letter currency code for `amount` (e.g. `USD`, `EUR`). Defaults to `USD` if omitted. example: USD callback_url: type: string format: uri description: > **Optional.** Legacy server callback URL. For new integrations, use Webhooks instead. Omit if you rely on webhooks. return_url: type: string format: uri description: > **Optional.** Where to send the customer after they finish or cancel checkout. Omit if you handle completion via webhooks only. metadata: type: object additionalProperties: true description: > **Optional.** Custom data attached to the invoice (e.g. `{"cart_id": "abc"}`). Returned in webhooks. Omit if you don't need extra fields. InvoiceCreateResponse: type: object properties: id: type: string pattern: ^(inv_|txn_|plink_|wh_|whd_|evt_|int_)[0-9a-z]{20,32}$ description: >- Unique invoice ID starting with `inv_`. Save this to check status or handle webhooks. status: $ref: '#/components/schemas/InvoiceStatus' checkout_url: type: string format: uri description: > Send your customer to this URL to pay (e.g. `https://pay.meum.io/...`). Open in a browser or redirect from your site. example: https://pay.meum.io/550e8400-e29b-41d4-a716-446655440000 payment_url: type: string format: uri description: >- Same as `checkout_url`. Kept for older integrations; prefer `checkout_url`. amount: type: string description: Invoice amount as a decimal string (e.g. `"100.00"`). example: '100.00' currency: type: string description: Currency code for `amount` (e.g. `USD`). example: USD output_asset: type: string description: Stablecoin you receive when paid (e.g. `USDC`). example: USDC expires_at: type: string format: date-time description: >- When this invoice stops accepting payment if still unpaid (UTC, e.g. `2025-09-01T14:31:44.171Z`). ErrorResponse: type: object description: > Legacy flat error shape retained for backward compatibility on invoice create and WooCommerce integration endpoints. properties: error: type: string description: Human-readable error message. example: Payout wallet not configured code: type: string description: Machine-readable error code for legacy endpoints. example: EXTERNAL_ORDER_INTEGRATION_CONFLICT details: type: object additionalProperties: type: string description: Optional key-value context with field-level validation errors. InvoiceStatus: type: string description: | Where the invoice is in the payment flow: - `pending`: created, not yet ready for payment - `quoted`: price quote ready; customer can proceed to pay - `awaiting_payment`: waiting for the customer to send funds - `paid`: payment received and confirmed - `underpaid`: customer paid less than the requested amount - `expired`: not paid before the deadline - `failed`: payment or processing failed - `refunded`: payment was returned to the customer - `cancelled`: invoice was cancelled before completion enum: - pending - quoted - awaiting_payment - paid - underpaid - expired - failed - refunded - cancelled securitySchemes: bearerAuth: type: http scheme: bearer description: | Store-scoped API key. Prefix with `sk_live_`. Example: `Authorization: Bearer sk_live_EXAMPLE_DO_NOT_USE` ````