Upgrade Transactions API

openapi: 3.0.3
info:
  title: Flex Pay API (Upgrade) Marketing Offers Transactions API
  description: Flex Pay (by Upgrade, formerly Uplift) lets travel and retail merchants offer Buy Now, Pay Later payment plans. The REST surface covers the Marketing Offers API (monthly-payment pricing offers early in the shopping flow), the Checkout Orders API (create, read, and confirm orders and retrieve the virtual-card payout resource), and the Transactions API (authorize, capture, void, refund — the Direct Settle disbursement model). All requests require an OAuth 2.0 access token obtained with the client-credentials grant and sent as a Bearer token.
  version: v1
  contact:
    name: Flex Pay Integration Support
    url: https://www.uplift.com/partners/
servers:
- url: https://partner.upgrade.com/api/checkout
  description: Production (checkout + transactions)
- url: https://partner.credify.tech/api/checkout
  description: Pre-production (checkout + transactions)
security:
- flexPayOAuth: []
tags:
- name: Transactions
  description: Transactions API (Direct Settle disbursement)
paths:
  /v1/transactions:
    post:
      operationId: authorizeTransaction
      tags:
      - Transactions
      summary: Authorize Transaction
      description: Using the order_id from the checkout flow, an authorization is the first step using the Transaction API. Once an authorization is submitted against an Order, a new Transaction is created. Once a transaction is authorized you have up to 7 days to submit capture requests; after expiration the remaining amount is automatically voided (see authorization_expiration on the Transaction object).
      externalDocs:
        url: https://docs.uplift.com/apidocs/authorize-transaction
      parameters:
      - $ref: '#/components/parameters/idempotencyKey'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              required:
              - order_id
              properties:
                order_id:
                  type: string
                  format: uuid
                  description: The order_id received from Flex Pay during the checkout flow.
                amount:
                  type: number
                  format: decimal
                  minimum: 0
                  description: The amount you're authorizing for this transaction. If left blank, authorize the remaining approved amount.
                currency:
                  type: string
                  description: The currency in which you're authorizing the transaction for, in ISO 4217 format. Required if amount is provided.
                merchant_reference_id:
                  type: string
                  description: Optional field for merchants to enter their own reference ID to aid in reconciliation.
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Transaction'
  /v1/transactions/{transactionId}:
    get:
      operationId: getTransaction
      tags:
      - Transactions
      summary: Get Transaction
      externalDocs:
        url: https://docs.uplift.com/apidocs/get-transaction
      parameters:
      - $ref: '#/components/parameters/transactionId'
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Transaction'
  /v1/transactions/{transactionId}/void:
    post:
      operationId: voidTransaction
      tags:
      - Transactions
      summary: Void Transaction
      description: Fully or partially void an already authorized transaction (e.g. a cancelled or unfulfillable item). The amount must be less than or equal to the remaining_amount in the Transaction object; voided amounts are permanently deducted and can no longer be captured.
      externalDocs:
        url: https://docs.uplift.com/apidocs/void-transaction
      parameters:
      - $ref: '#/components/parameters/idempotencyKey'
      - $ref: '#/components/parameters/transactionId'
      requestBody:
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/TransactionAmountRequest'
      responses:
        '200':
          description: Updated Transaction object
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Transaction'
  /v1/transactions/{transactionId}/capture:
    post:
      operationId: captureTransaction
      tags:
      - Transactions
      summary: Capture Transaction
      description: Request payment for the customer's order. Fully capture by submitting an amount equal to the remaining_amount, or partially capture with a smaller amount and request the rest later.
      externalDocs:
        url: https://docs.uplift.com/apidocs/capture-transaction
      parameters:
      - $ref: '#/components/parameters/idempotencyKey'
      - $ref: '#/components/parameters/transactionId'
      requestBody:
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/TransactionAmountRequest'
      responses:
        '200':
          description: Updated Transaction object
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Transaction'
  /v1/transactions/{transactionId}/refund:
    post:
      operationId: refundTransaction
      tags:
      - Transactions
      summary: Refund Transaction
      description: Fully or partially refund a previously captured transaction with an amount equal to or less than the captured_amount. The refunded amount is returned by netting against your upcoming payout during the disbursement process.
      externalDocs:
        url: https://docs.uplift.com/apidocs/refund-transaction
      parameters:
      - $ref: '#/components/parameters/idempotencyKey'
      - $ref: '#/components/parameters/transactionId'
      requestBody:
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/TransactionAmountRequest'
      responses:
        '200':
          description: Updated Transaction object
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Transaction'
components:
  schemas:
    TransactionAmountRequest:
      type: object
      properties:
        amount:
          type: number
          format: decimal
          minimum: 0
          description: Amount voided, captured, or refunded. Optional. If left blank, uses the full remaining amount.
        currency:
          type: string
          description: ISO 4217 currency code for this transaction. Required if amount is provided.
        merchant_reference_id:
          type: string
          description: Optional field for merchants to enter their own reference ID to aid in reconciliation.
    Transaction:
      type: object
      description: The Transaction object returned by the Transactions API (documented subset).
      properties:
        id:
          type: string
          format: uuid
          description: The unique transaction_id generated when an authorization is submitted for an order.
        original_amount:
          type: number
          format: decimal
          description: The original amount the transaction was authorized for.
        remaining_amount:
          type: number
          format: decimal
          description: The remaining amount that can be captured.
        captured_amount:
          type: number
          format: decimal
          description: The cumulative amount that has been successfully captured.
        authorization_expiration:
          type: string
          description: Timestamp after which no new captures may be placed on this transaction and the remaining amount is automatically voided (up to 7 days after authorization).
  parameters:
    idempotencyKey:
      name: Idempotency-Key
      in: header
      required: true
      description: Idempotency key to prevent duplicate requests.
      schema:
        type: string
    transactionId:
      name: transactionId
      in: path
      required: true
      schema:
        type: string
        format: uuid
  securitySchemes:
    flexPayOAuth:
      type: oauth2
      description: 'OAuth 2.0 client-credentials grant. Client IDs and secrets are issued per merchant and per environment by the Flex Pay integration team (server IP allowlisting required). Tokens expire after 30 minutes by default and are sent as `Authorization: Bearer {token}`.'
      flows:
        clientCredentials:
          tokenUrl: https://partner.upgrade.com/api/auth/v1/oauth/token
          scopes: {}
    bearerAuth:
      type: http
      scheme: bearer
      description: Access token from the Flex Pay authorization server, included in the Authorization HTTP header for all API requests.
externalDocs:
  description: Flex Pay REST API reference
  url: https://docs.uplift.com/apidocs
x-generated: '2026-07-21'
x-method: generated
x-source: Generated faithfully from the published Flex Pay REST API reference at https://docs.uplift.com/apidocs (Upgrade, Inc. — Flex Pay, formerly Uplift). Upgrade does not publish a machine-readable OpenAPI; every path, method, parameter, and field below is taken from the documented reference pages (creates-an-order, retrieves-an-order, confirms-an-order, retrieves-an-orders-card-resource, authorize-transaction, void-transaction, capture-transaction, refund-transaction, get-transaction, generates-marketing-offers-for-orders-4, authorization-1). Schemas capture the documented subset of fields, not the full internal model.