Agile Law Execution Factory (ALEF)

The Agile Law Execution Factory (ALEF) is developed by the Dutch Tax Administration (Dutch: Belastingdienst) to enable non-programmers to write business rules for Dutch law in the language Regelspraak, which is still comprehensible to law experts and at the same time precise enough to be executed by a computer.

See for more information:

• ALEF user documentation: https://wendbarewetsuitvoering.pleio.nl (in Dutch).
• Regelspraak: https://regels.overheid.nl website (in Dutch).

Build

Make sure you have the following dependencies installed on your system:

• OpenJDK 17 or newer.
• Maven.
• Zensical (optional), this is for the documentation

To build a ALEF Studio run mvn -U package when this is successful in the build/artifacts/alef-distribution you wil find a distribution for Windows, Linux and MacOS to use.

Developing

1. Make sure you installed the following software on your system:
   • OpenJDK 17 or newer.
   • Maven.
2. Make sure you install Jetbrains MPS see the version-mps.txt file for the version to use.
3. Run mvn -B -U -Pinstall-deps package to only build and install the dependencies.
4. Open in MPS the folder where this README.md file is located.
5. Add to Settings > Appearance & Behavior > Path Variables
   • alef.home the location where README.md file is located.
6. Run Build > Rebuild Project to build ALEF.

Documentation

To build the documentation:

1. Make sure you installed Python 3.x and Zensical (pip install zensical)
2. Run: sh scripts/build-docs.sh

After building the documentation is available in build/docs

Security

The Dutch Tax Administration (Dutch: Belastingdienst) promotes the practice of responsible vulnerability disclosure. If you discover a vulnerability, we encourage you to report it to us so we can address it promptly. For details on how to report a security vulnerability, please refer to our security policy.

Contributing

We are excited to work alongside you, our amazing community, to build and enhance ALEF!

Before you start work on a feature/fix, please read & follow our Contributor's Guide to help avoid any wasted or duplicate effort.

License

Copyright 2026, Dutch Tax Administration (Dutch: Belastingdienst). ALEF is released under European Union Public License (EUPL) 1.2. See the LICENSE file in this repository for details. There might be a translation in your language available at https://joinup.ec.europa.eu/collection/eupl/eupl-text-eupl-12.