Merchantware 4.6

What is the Merchantware API?

Using the Merchantware API, you can integrate your POS solution with our gateway. The Merchantware API is made up of different endpoints that facilitate transaction processing and provide reporting tools. Integrating with the Merchantware API enables your POS solution to process the following payment methods:
  • Credit cards and debit cards
  • Checks and checking account payments
  • Gift cards and loyalty cards

Integration Requirements

When you are programming your integration, be aware of the following:

  • SOAP specifications
  • Flexibility requirements
  • Authentication requirements

SOAP specifications

We use SOAP version 1.2 for code examples. SOAP 1.2 requires a Content-Type header of “application/soap+xml; charset=utf-8”.

Important: Do not include the SOAPAction header that we previously used for SOAP version 1.1 code examples.

Flexibility requirements

Your integration must have the flexibility to handle new response parameters from our gateway because we regularly update our API. When building your integration, you must not do the following:

  • Hardcode the sequence of the parameters that you expect us to return in the response
  • Use hand-written tools to construct or parse XML, SOAP, or JSON
  • Use any features in your toolchain that run strict validation
  • Use field ordinals to find specific information in a response

Authentication requirements

To authenticate your requests, you must send the MerchantCredentials object in every request.

Note: We send the merchant their credentials when they open their account.


Parameter Description Type Size
MerchantName Name of the merchant or their business. String 1-160
MerchantSiteId Identifier for the merchant's store or location. String 8-160
MerchantKey Authentication key for the merchant’s account. String 1-160


Your integration must use the current version of our API, which is Merchantware 4.6.

Important: Do not use more than one version of our API in your integration. If your integration uses Merchantware 4.5, we recommend that you update your integration to use only Merchantware 4.6.

Legacy API versions

For legacy API documentation, click the following links:


If you have any questions about your integration, contact the Certification Engineering Team at