Welcome to the EMS development portal

A space where developers and product owners can access easy-to-use API keys to integrate online payments directly into your desired website.

A How-To Guide to Accepting Payments

From software developers, to website managers, to webshop owners this is the place for all things related to EMS Online its APIs and documentation. We’re here to help with any transaction, any way.

Given the different levels of coding (and financial) expertise of our users, we try to explain things at different levels. If you have been at this for a while, then use the left-hand pane to navigate straight to the codes and access keys.

If you’re newer to things, our portal is set up to educate and inform as you work through the steps. This page provides an overview of the EMS Online API and how get started with them, so if you identify yourself as less experienced, then just keep scrolling.

Getting Started

Step 1 – Get to know our 3 integration options

Plugins are the easiest to integrate into your web store’s shopping cart – no manual coding is required. Simply install the plugin, enter the EMS credentials, and activate the payment method. You’re now ready to accept payments!

An HPP solution manages customer redirections required in the checkout process and allows clients to use EMS Online hosted payment pages. Added advantage? This significantly reduced the burden of PCI compliance for merchants as they do not store sensitive cardholder information.

If you already are fully compliant but seeking a better user experience, then this fully customizable option is the best for you. Here the cardholder selects the payment method in your webshop rather than on the EMS Online hosted payment page.

Step 2 – Testing

Of course there are some parallel steps that have been omitted (like signing a contract), but a picture is worth a thousand words. Here’s the visual overview:


Step 3 – Get in touch for further support

EMS REST API: Safe, Secure, Reliable

EMS Online makes use of a REST API with a JSON body.

Also referred to as RESTful API, this fancy acronym refers to an architectural style for an application program interface (API) that uses HTTP requests to access and use data.


Essentially an API is a website code that allows two software programs to communicate – the API spelling out the instruction and parameters of this communication.


In the REST architectural style, the implementation of the client and the implementation of the server can be done independently without each knowing about the other. Added bonus? REST tends to use less bandwidth.


The API key is used as means of authentication and requires HTTPS connections encrypted via TLS1.2 (or newer). Older versions of SSL and TLS are vulnerable, therefore, they are no longer supported.

Use this API url: api.online.emspay.eu. Jump to the REST API Authentication and HTTP status codes for more information.