Nantes Métropole's Public Algorithm Registry — France's First Open-Sourced Municipal Algorithms

On 6 October 2020, Nantes Métropole became the first metropolitan-level authority in France to publish the source code of two algorithms it operates: those setting reduced water tariffs and reduced public-transport fares for low-income residents. The move fulfilled a commitment the metropolitan area had made in its June 2019 data charter, and coincided with a national legal obligation, in force from 1 July 2020, requiring public bodies to inform citizens when automated systems are used in individual administrative decisions (Code des relations entre le public et l'administration, art. L.312-1-3, from the 2016 Digital Republic Law).
Rather than publish to a code-sharing platform like GitHub, Nantes Métropole chose its own open-data portal (data.nantesmetropole.fr) specifically to prioritise public accessibility over developer convenience. The approach followed guidance from Etalab, the French government's open-data and algorithm-transparency unit. In 2025 the metropolitan area folded this work into an updated "Charte de la donnée métropolitaine et de l'IA" (Metropolitan Data & AI Charter), adding AI-specific commitments — including a ban on biometric-identification uses and a required comparison against non-AI alternatives — on top of the original transparency pledge, with three implementation-review rounds published since 2020.
Public reporting documents two named algorithms opened in 2020 and a charter with periodic reviews since; there is no published count of how many additional algorithms have since been added to the registry, so the scale of expansion beyond the original two remains unconfirmed.

Read the full analysis: https://data.nantesmetropole.fr/pages/algorithmes_nantes_metropole/