WHMCS Accounting Software Electronic Invoice Integration

Introduction

Electronic Invoicing is spreading around the world and is quickly becoming mandatory in many countries. Billing Extension brings Italian and Slovene E-Invoicing integration with WHMCS but can also help with other countries.

Before we dig deeper into the topic, keep in mind that electronic invoicing works differently in every country. For instance there's no way one can use Italian e-invoicing in any country other than Italy. Platforms are not interchangeable.

We would like to integrate all platforms with WHMCS but there are huge differences in regulations not counting technological aspects. Let us put it into perspective.

Integrating Italian e-invoice took us 4 months work and keeping it functional is a process that never stops. It would be prohibitive for us to go through the same thing for tens of different platforms but there's a good news.

There is a common thread through every implementation of electronic invoicing. In one way or another, they all rely on the same information and billing concepts like credit note, VIES, invoice shapshot, billing error detection, monthly invoicing etc.

Instead of leaving you with no option other than creating your own implementation from scratch, we came up with the idea of including in our module a plugin that provides you with all information you need to integrate any e-invoce platform.

We understand that the idea of completing the integration on your own is daunting. Not to mention you still need to hire a developer but you just need to take care of the final step. Allow us to explain you what we mean.

When it comes to integrating e-invoice platforms, the most challenging part is collecting information from WHMCS. We are not simply referring to things like customers' details and VAT numbers.

There are other things that require WHMCS to understand billing concepts that it is not aware of. For example intra/extra EU, the correct use of credit, MOSS, VIES, the difference between invoice, proforma and credit note and so on.

That's where Billing Extension combined with this plugin comes to help. It gives you everything you need to get billing data out of WHMCS and feed your accounting software or e-invoice system.

With this solution you don't need to hire a WHMCS developer. They are as rare as hen's teeth nowadays. All you need is a "general purpose" developer capable of using this information to get the result you expect.

Be it generating XML or CSV files (electronic invoices) and transmit them via FTP or HTTP to Revenue Agency, accounting software or an intermediary platform.

As you see, Billing Extension already gives you everything you need. You just need to complete the final step. In the following chapters we are going to explain you how to use this feature.

Getting Started

Begin by visiting Addons > Billing Extension > Settings and click "plus" icon to activate WebService.

Once done, go back to Settings and expand the newly added section. Here you find WebService configuration. At the moment of writing this, it only has one parameter named Token.

This randomly generated string is used to establish a secure connection for transmissions of data. Press the orange button to generate the token and save.

We prepared this PHP script with comments to show you how easily you can interact with our web service. We used the same principle WHMCS External API. In essence send a curl() request and receive the response in json array.

Authentication

Authentication requires two parameters. At some point we were also thinking of using OAuth 2.0 but it was a bit overkill.

API Get

Use this command to retrieve from WHMCS billing details enriched and validated by Billing Extension. Multiple filters are available.

It is worth noting that ClientData values come from Invoice Snapshots therefore they're safe to use of billing purposes. Moreover such values are trimmed to remove whitespace from both ends of strings.

Errors

We made our WebService user-friendly. In practical terms when there's something wrong in your API request, WebService provides clear details about the error directly in the json response. Such errors are not cryptic but give a full description about what went wrong.

Date Keywords

When it comes to dates, the WebService supports special keywords that help you filtering records by predefined intervals listed in the table below. Monday is considered the first day of the week and the provided descriptions assume that current date is Saturday 2019-06-15.