Overview

Addons in GOBL have a similar objective to namespaces in XML documents, but with super-powers; they provide additional normalization methods, validation rules, and extension definitions, alongside scenarios and tags, that augment the basic functionality of the GOBL document.

When an addon is applied to a GOBL document that supports them, the calculation and validation steps will automatically use all the addon’s specifications to ensure that all the data complies with whatever is required by the standard or format represented.

A great example of this is the mx-cfdi-v4 addon. When applied to an invoice, it will automatically ensure that any extensions and validation rules are performed, so that document can subsequently be processed by a conversion tool into the local XML CFDI format, in the case, gobl.cfdi.

The key advantage with addons is that the original content of the GOBL invoice is still intact, maintaining the global compatibility, but ensuring that any local or format restrictions are accounted for.

Support for addons was included in the v0.200.0 release of GOBL.

External Addons

Most addons are bundled with the GOBL library itself, but some are maintained in their own Go modules — for example, the French CTC addons live in gobl.fr.ctc. GOBL core keeps a curated list of approved external addons so that their keys remain valid $addons values in the JSON Schema, but recognition is not the same as availability: a document declaring an external addon can only be calculated or validated by an application that imports the addon’s module, which registers its extensions, normalization, and validation rules.

External addon pages in this section are marked with a note linking to the module that implements them.