Application Programming Interface

InvoiceXpress Documentation


What’s an API and what is it for?

API (Application Programming Interface) is a way for third party developers to integrate InvoiceXpress into their applications, allowing them to send invoices programatically without visiting the InvoiceXpress website.

The InvoiceXpress API uses a REST aproach and accepts XML as a request format. On HTTP POST and PUT requests do not forget to specify:

“Content-Type: application/xml; charset=utf-8”.

An example: let’s say you have an online store, and need to invoice your clients after each successful purchase, normally you had to develop all the code to manage the creation and sending of the invoice (with all the underlying logic, e.g. managing clients, products, taxes, invoice numbering, etc.).

Using the InvoiceXpress API you just need to make an HTTP POST request with the invoice data as XML to our API to create one.

XML special characters

Certain characters cannot be used within XML because they have special meanings. These characters have to be escaped with the following code. To use one of the characters listed below, substitute it with the appropriate code.

Special character Code
ampersand (&) is escaped to &
double quotes (“) are escaped to "
single quotes (‘) are escaped to '
less than (<) is escaped to &lt;
greater than (>) is escaped to &gt;