About LEOS - Open Source software for editing legislation

LEOS (Legislation Editing Open Software) is an open source software designed to help those involved in draſting legislation, which in itself is a complex knowledge-intensive process, by supporting efficient online collaboration. Comments, suggestions, version control, co-edition, everything is there. Regarding the structure, that is where we aim to be as restrictive as possible and this is not because we are conservative, but because this helps the draſters follow the rules and avoid mistakes. Content is stored in an XML format, currently Akoma Ntoso V3.

LEOS is currently supported by the Digital Europe Programme (DIGITAL).

Important to note that our journey started under ISA Programme with ISA Action 1.13. LEOS - Legislation Editing Open Software, when we first developed a better understanding of the way public administrations address the issue of drafting their legislations, with a view to identify best practices, improvements and areas where common efforts and developments are possible. We also invested time on researching the best open standards and tools so that we could be cost efficient and deliver open source for our community. And we keep doing this every time we need to add new features. Having identified an opportunity in the field, the project delivered various proof of concepts and prototypes. Now we have an execution phase every year where we constantly improve our tool.

After ISA Action 1.13, LEOS continued under ISA² Action 2016.38 Legislation Interoperability Tools – LegIT until the end of ISA² Programme.

The latest prototype supports the drafting of the 'secondary' legislation of the EU law which has to be adopted under the Ordinary Legislative Procedure. Therefore, it covers the writing of Proposals for Directive, Decision and Regulation submitted by the Commission to the Council and the Parliament. If you want to find out more about this procedure, please read the European Parliament's article.

More information on Digital Europe Programme (DIGITAL) here.

More information on the ISA² Action available here.

Owner/Contact Information

European Commission
Contact information


Solution type
Technical Specification
Interoperable European Solution Service
Under development


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