Definition
STET (Systèmes Technologiques d'Échange et de Traitement) is a French company created by the major French banks.
It plays two key roles: operating the CORE(FR) clearing system (French SEPA transfers and direct debits) and publishing the reference PSD2 API that most French banks implemented for their compliance.
STET vs Berlin Group
When PSD2 arrived, three API standards emerged:
- STET — driven by the French banks (and the Belgian community): REST + JSON + OAuth2 + HTTP-signature, based on ISO 20022.
- Berlin Group / NextGenPSD2 — driven by German, Austrian and Nordic banks, the broadest geographically.
- OB UK — the British standard, more exhaustive, but outside the EU since Brexit.
For a French fintech, mastering STET is essential; to scale across Europe, you also have to handle Berlin Group (and OB UK for the UK market).
What STET (the company) does
- Operates CORE(FR): the main French interbank clearing platform, classified as a systemically important payment system since 2014. More than 36 billion transactions processed in 2024 across all its platforms.
- Publishes the PSD2 API spec (version 1.6.3, Oct. 2022): AIS, PIS, CBPII endpoints, consent models, error handling.
- Runs the community of implementing banks (versions, evolutions, regulatory alignment).
What STET does not do
- It authorises no one: it is the ACPR that grants authorisations.
- It does not write the regulation: it translates PSD2 and the RTS into an implementable spec.
- It does not operate the banks' API: each ASPSP hosts its own instance, with its own particularities.
- It is not a regulator: a private company owned by the banks.
In the PSD2 ecosystem
STET is the technical building block that lets a French TPP connect to the major banks with a single integration logic — in theory, because in practice each bank has its own subtleties.
Concrete examples
- Banks on STET: BNP Paribas, Société Générale, LCL, Crédit Agricole, BPCE, La Banque Postale, Crédit Mutuel — the overwhelming majority of the French market.
- Banks on Berlin Group: Revolut, N26, HSBC France and most DACH or Scandinavian banks — to cover the whole market, you have to handle both standards.
- Implementation variations: even on STET, two banks can diverge on date format, error handling, endpoint availability or SCA smoothness — hence the value of aggregators (Bridge, Tink, Yapily).
- Versioning: the spec evolves regularly (1.4 → 1.5 → 1.6), at different paces depending on the bank — a point to anticipate in an integration project.