# Integrations & API's

- [Single Transaction API (TxHandler)](/transaction-processing/integrations-and-apis/single-transaction-api-txhandler.md)
- [REST API](/transaction-processing/integrations-and-apis/rest-api.md)
- [Site - SID - Payments](/transaction-processing/integrations-and-apis/rest-api/site-sid-payments.md)
- [Transaction - ptxid](/transaction-processing/integrations-and-apis/rest-api/transaction-ptxid.md)
- [Merchant Management](/transaction-processing/integrations-and-apis/rest-api/merchant-management.md): API's to create and manage merchants
- [Fraud Check](/transaction-processing/integrations-and-apis/rest-api/fraud-check.md)
- [Payment Refund](/transaction-processing/integrations-and-apis/rest-api/payment-refund.md)
- [Field Definitions](/transaction-processing/integrations-and-apis/field-definitions.md): Common Field and their definitions
- [Responses](/transaction-processing/integrations-and-apis/responses.md)
- [Testing Data](/transaction-processing/integrations-and-apis/testing-data.md)