# Merchant API Reference

## Merchant API Reference

- [Introduction](https://docs.payengine.co/merchant-api-reference/introduction.md)
- [Authentication](https://docs.payengine.co/merchant-api-reference/authentication.md)
- [Credit Card Authorization V2](https://docs.payengine.co/merchant-api-reference/transactions/credit-card-authorization-v2.md): Authorizes transaction immediately but is not flagged for settlement. Authorized transactions must be capture to settle.
- [Void Credit Authorization](https://docs.payengine.co/merchant-api-reference/transactions/void-credit-authorization.md): Void an existing credit card authorization before capture
- [Credit Card Capture](https://docs.payengine.co/merchant-api-reference/transactions/credit-card-capture.md): Credit card capture converts an authorized transaction into sale and flags it for settlement.
- [Credit Card Sale](https://docs.payengine.co/merchant-api-reference/transactions/credit-card-sale.md): The credit card sale API obtains real-time authorization for a Credit Card Sale transaction and enters the transaction into the Unsettled batch
- [ACH Sale](https://docs.payengine.co/merchant-api-reference/transactions/ach-sale.md): The ACH Sale API debits the purchase amount from provided bank account
- [Refund](https://docs.payengine.co/merchant-api-reference/transactions/refund.md)
- [Credit](https://docs.payengine.co/merchant-api-reference/transactions/credit.md)
- [Search Transactions](https://docs.payengine.co/merchant-api-reference/transactions/search-transactions.md)
- [List Transactions](https://docs.payengine.co/merchant-api-reference/transactions/search-transactions/list-transactions.md): The purpose of transaction API is to provide users with an ability to access the transaction related reports and merchant reports via API.
- [Transaction Detail](https://docs.payengine.co/merchant-api-reference/transactions/search-transactions/transaction-detail.md)
- [Testing](https://docs.payengine.co/merchant-api-reference/transactions/testing.md)
- [Secure Fields Overview](https://docs.payengine.co/merchant-api-reference/secure-fields/secure-fields-overview.md)
- [SecureFields Bank Account](https://docs.payengine.co/merchant-api-reference/secure-fields/secure-fields-overview/securefields-bank-account.md)
- [Using tokens](https://docs.payengine.co/merchant-api-reference/secure-fields/secure-fields-overview/using-tokens.md)
- [SecureFields JS Properties & Styling](https://docs.payengine.co/merchant-api-reference/secure-fields/secure-fields-overview/securefields-js-properties-and-styling.md)
- [Available Webhooks](https://docs.payengine.co/merchant-api-reference/webhooks/available-webhooks.md)
- [ISO Currency Codes](https://docs.payengine.co/merchant-api-reference/error-and-response-codes/iso-currency-codes.md)
- [Response codes](https://docs.payengine.co/merchant-api-reference/error-and-response-codes/response-codes.md)
- [Address Verification Codes](https://docs.payengine.co/merchant-api-reference/error-and-response-codes/address-verification-codes.md)
- [CVV (Cardholder) Verification Codes](https://docs.payengine.co/merchant-api-reference/error-and-response-codes/cvv-cardholder-verification-codes.md)
- [Commercial Card Codes](https://docs.payengine.co/merchant-api-reference/error-and-response-codes/commercial-card-codes.md)
- [Authorization characteristics indicators](https://docs.payengine.co/merchant-api-reference/error-and-response-codes/authorization-characteristics-indicators.md)
- [Universal cardholder authentication field](https://docs.payengine.co/merchant-api-reference/error-and-response-codes/universal-cardholder-authentication-field.md)
- [Mastercard purchase transaction type](https://docs.payengine.co/merchant-api-reference/error-and-response-codes/mastercard-purchase-transaction-type.md)
- [ACH host response codes](https://docs.payengine.co/merchant-api-reference/error-and-response-codes/ach-host-response-codes.md)
- [ACH host transaction statuses](https://docs.payengine.co/merchant-api-reference/error-and-response-codes/ach-host-transaction-statuses.md)