OpenFisca

The most widely adopted free and open-source engine to write Rules as Code

Owner

OpenFisca Association

Non-Profit Organisation

Contact information

OpenFisca Association

https://openfisca.org

OpenFisca enables collaboratively modelling laws and regulations and making them computable over open APIs.

Policy experts and governments

OpenFisca enables institutions to efficiently share regulation updates and to pool IT costs. Interconnecting rules across public bodies in the form of legible parameters and executable code provides algorithmic transparency and reduces the bill for the taxpayer.

Developers and datascientists

OpenFisca enables developers to easily deliver apps calculating complex taxes and benefits through its JSON web API, and datascientists to compute large-scale through its vectorial Python API. Contributing formulas and coding extensions enables building services for any business.

Economists and researchers

OpenFisca enables economists and researchers to use survey and administrative data to simulate the impact of any past or future reform. Linking all computed taxes and benefits enables analysing how multiple reforms interact.

Example use cases

Here is a selection tailored for public actors. See more on the dedicated showcase.

A classic use case of Rules as Code is to enable citizens to calculate their eligibility to social benefits. OpenFisca, thanks to its ability to model all forms of legislation, enables this in many countries:

🇫🇷 Portail National des Droits Sociaux, by the French Social Security.
🇫🇷 MesAides28, by the Eure-et-Loir local government.
🇪🇸 Les Meves Ajudes, by the City Council of Barcelona.
🇯🇵 支援みつもりヤドカリくん (Shien Yadokari), by the Institute for Poverty Prevention.
🇳🇿 BenefitMe, by a New Zealand citizen group.

The rules that can be modelled, however, go way beyond benefit entitlement and can enable simulating the impact of reforms, such as with:

🇫🇷 LexImpact, by the French National Assembly.
🇬🇧 PolicyEngine UK, by PolicyEngine.

Other usages were prototyped such as:

🇨🇦 The city of Vancouver interconnected OpenFisca with their geographical information system to calculate eligibility to opening a business in a neighbourhood.
🇦🇺 The state of New South Wales used OpenFisca to assess eligibility to a business permit and to construction bonuses.

OpenFisca is a sustainable, contributive digital common

OpenFisca is developed by many contributors, from public agencies to private companies to individual contributors to academics improve the codebase and contribute to the model, reading the legislation and transforming it into code.

The OpenFisca Association oversees its governance with the purpose to “guarantee worldwide, free and permanent access to and contribution to the OpenFisca software suite, its collaborative processes and its national and local models”, ensuring long-term sustainability.

Codebase

OpenFisca is written in Python, a very popular programming language for which it is easy to find developers. It is published under the open source GNU Affero General Public Licence. The OpenFisca Core source code is referenced on its own page in the EU OSS Catalogue.