openapi: 3.0.3
info:
  title: Juspay Express Checkout Customers Transactions API
  description: 'Server-to-server REST API for the Juspay payments orchestration and checkout platform. Merchants create and track orders, process transactions across payment methods (cards, UPI, netbanking, wallets), issue refunds, manage customers, and initialize the Hyper Checkout / HyperSDK drop-in checkout via a payment session. Requests authenticate with an API key over HTTP Basic (API key as the username, empty password) plus an `x-merchantid` header; Juspay recommends passing an `x-routing-id` (typically the customer id) to pin the payment session lifecycle. Most write endpoints accept `application/x-www-form-urlencoded` bodies.

    Endpoint paths and methods below are grounded in Juspay''s public Express Checkout / Hyper Checkout documentation as of 2026-07-12. Request and response schemas are modeled from the documented parameters and are marked where fields are illustrative rather than exhaustive; verify against the live reference before production use.'
  version: '1.0'
  contact:
    name: Juspay
    url: https://juspay.io/in
servers:
- url: https://api.juspay.in
  description: Production
- url: https://sandbox.juspay.in
  description: Sandbox
security:
- basicAuth: []
tags:
- name: Transactions
  description: Server-to-server transaction processing against an order.
paths:
  /txns:
    post:
      operationId: createTransaction
      tags:
      - Transactions
      summary: Create a transaction
      description: Server-to-server transaction endpoint that processes a payment against an existing order with a chosen payment method (card, UPI, netbanking, wallet). Documented as exempt from the standard order authentication flow. Body fields below are modeled from the documented flow and are not exhaustive.
      parameters:
      - $ref: '#/components/parameters/MerchantId'
      - $ref: '#/components/parameters/RoutingId'
      requestBody:
        required: true
        content:
          application/x-www-form-urlencoded:
            schema:
              $ref: '#/components/schemas/TransactionInput'
      responses:
        '200':
          description: Transaction result / next action.
          content:
            application/json:
              schema:
                type: object
                additionalProperties: true
        '401':
          $ref: '#/components/responses/Unauthorized'
components:
  parameters:
    RoutingId:
      name: x-routing-id
      in: header
      required: false
      description: Routing key that pins the payment session lifecycle - typically the customer_id, or an order/cart id for guest checkout.
      schema:
        type: string
    MerchantId:
      name: x-merchantid
      in: header
      required: true
      description: Merchant ID issued by Juspay.
      schema:
        type: string
  schemas:
    Error:
      type: object
      properties:
        status:
          type: string
        error_code:
          type: string
        error_message:
          type: string
    TransactionInput:
      type: object
      required:
      - order_id
      - payment_method_type
      properties:
        order_id:
          type: string
        payment_method_type:
          type: string
          description: e.g. CARD, UPI, NB (netbanking), WALLET.
        payment_method:
          type: string
        redirect_after_payment:
          type: boolean
        format:
          type: string
          description: Response format, e.g. json.
  responses:
    Unauthorized:
      description: Missing or invalid credentials.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
  securitySchemes:
    basicAuth:
      type: http
      scheme: basic
      description: 'HTTP Basic authentication. The API key is the username and the password is an empty string; the pair is Base64-encoded into `Authorization: Basic <credentials>`. An `x-merchantid` header is also required on requests.'