APIs and ISO 20022

APIs

In November 2017, 23 countries under the governance of ISO TC68 Financial Services agreed to work together on defining a framework for a standardised API ecosystem. The working group produced technical specifications for web-based API (WAPI) standardization. The document can be bought from the ISO website.

APIs and ISO 20022

An API is a set of functions and protocols that application software uses to invoke services and provide greater functionality to applications or to websites. Data accessed via an API may be closed, shared or open, however to expose a consistent view of data to an API, it requires the data to be uniformly presented. When APIs are implemented as part of an ecosystem, ISO 20022 can add value by providing the common business process data semantics to be used in those API based exchanges.

There is a significant opportunity to define a consistent approach for building APIs based on the ISO 20022 business model. In 2018, members of the Registration Management Group (RMG) published a whitepaper exploring how ISO 20022 message-level data could be transformed into JSON syntax. This work helped clarify how JSON could serve as an alternative to ISO 20022 XML, although it addressed a different challenge than defining APIs themselves.

Bringing this work forward, an API WG has been constituted to define a governance and registration process of standardised API resources.  A proof of concept was launched to support this process in the Account Management business area, this proof of concept is based on BJ 178.

As part of ongoing efforts to enhance the ISO 20022 ecosystem, the Technical Support Group (TSG) has developed a set of updated whitepapers, which was approved by the RMG in June 2025. To support the next phase of this work, the API Working Group has been formally established as a full API Standards Evaluation Group (SEG). Drawing on insights from early implementation efforts, the API SEG has adopted a set of key recommendations that guide the development of standardized API resources aligned with ISO 20022, along with a robust governance and registration framework.

Two whitepapers are now available to support implementers and stakeholders:

• Generation of the JSON Schema (DRAFT 2020-12) – This paper outlines how ISO 20022 message definitions can be transformed into JSON Schema, providing a technical foundation for JSON-based implementations.
• ISO 20022 and Web APIs – Implementation Best Practices – This paper offers guidance on how to design and implement APIs that are aligned with ISO 20022 semantics and governance principles.

These whitepapers can be accessed in the section JSON and API whitepapers below.