Welcome to the PaymentExpress Developer Portal!

You have likely received this link from the Grant Street Group team as a warm up to your potential or upcoming implementation with our payment APIs.

While we offer different integration methods, the requirements for your integration make an “Embedded In Person Checkout” the best choice for your implementation within our ecosystem. This integration style uses PIN Pads attached to cashiering workstations to take payments through your application using our powerful and yet simple API and workflows.

All of these parts of the process are well documented within our Guide to Embedded In Person Payments. Below are a few links we think will help you get a better feel for this sort of implementation:

Our Developer Portal documentation (available at https://docs.gsg.tech) offers a full API reference section, which documents in detail all the parameters available and required by our various APIs. You can try these APIs out in our non-production environments by registering for an account at the link above. This will allow you to use the Developer Portal to create carts in our non-production environment - either in generic client sites or, once configured, the non-production versions of your own PaymentExpress sites.

Once we have nailed down the details for your implementation, this documentation will be updated and customized to your implementation, including the necessary values for required API fields. Please have a look through this documentation, and let us know if you have any questions!