OpenAPI Specifications

Our API history stretches back over 20 years, since we first published our own HTTP Message Transmission Guidelines.

Initially, API specifications were often proprietary or ad hoc, meaning that each API provider had its own format for documenting APIs, making it challenging for developers to work with multiple APIs consistently. 

At the time, we were ahead of the curve but technology and capability has evolved to streamline API development and consumption, fostering interoperability and simplifying the process of building and interacting with APIs, which led to the development of OpenAPI specifications. 

An OpenAPI Specification (formerly known as Swagger Specification) is a standard format used to describe APIs. 

It's a machine-readable document that defines the endpoints, request parameters, response formats, authentication methods, and other details necessary for interacting with an API.

The specification is written in YAML or JSON format and serves as a contract between the API provider and users. It allows developers to understand how to interact with the API without needing to inspect its implementation details, promoting interoperability and simplifying the process of building client applications that integrate with the API. 

OpenAPI Specifications are often used for documenting APIs, generating libraries, and automating various aspects of API development and testing. They facilitate communication between different teams involved in API development, such as backend and frontend developers, and API users.

Operating as a not-for-profit, Criterion collaborates with the industry as an independent third party to create Standards and improve efficiencies in the financial services sector.

We have been providing the backbone for the exchange and movement of data between organisations for almost 30 years.

In addition to driving efficiencies, we are uniquely positioned to facilitate and drive cross-industry engagement, helping organisations achieve higher levels of collaboration, reduce costs and achieve better customer outcomes.