Drupal - Xero Invoicing
We built this Drupal module for our own use and now offer it free to everyone.
It is for Drupal 6, however we are currently in the process of porting it to Drupal 7 - if you'd like to part-sponsor this, please let us know and we'll get it done more quickly!
Basically, it creates a link between a Drupal website and a Xero account and takes care of the relevant Xero application authentication. You do need to create some security keys, instructions for doing so are included within the attached files - as are reasonably detailed instructions for installation and configuration steps.
On installing the module, a Drupal Invoice content type is created, with fields that map across to the relevant line item details in a Xero invoice. It also synchronises contacts between a Contact content type and Xero Contacts.
On cron, the Drupal site calls into Xero, makes sure the contacts are synchronised, and then creates new Xero invoices from new Drupal invoice nodes.
We're making this module freely available, on the basis that there are limits to the amount of free support we can offer, and, it was built for our specific requirements. For both of these reasons this module has not been contributed, if you have requirements that go beyond this module, or want to sponsor additional development and contribution, then get in touch and we can run through things.
You will also need to install the dependency - cck_line_product, which adds some custom fields types for use in your invoice content type.