There are versions available for all major platforms and if many minor ones; most are quite straightforward to implement. If you are already equipped for social logins such as Google accounts, Facebook or Twitter you may already be using it.
At the basic level, OpenID only does authentication - i.e. is the user who they say they are; OAuth is for finding out information about the user such as identifiers and affiliations. OpenID Connect does both of those, which is what you need when you are dealing with institutional customersenables the authentication and the retrieval of information you can authorise on in one compact package.
What is OpenAthens?
OpenAthens (originally just Athens) was introduced in 1995 and was one of the first federated access management solutions in the world. It has evolved over time to embrace new technologies as they emerged such as SAML and now OIDC.
Why do I want to join SAML federations using OpenAthens?
SAML federations are where you will find the customers who buy institutional subscriptions and site licences such as Universities, Colleges, Hospitals, Government departments, and Multi-National corporations.
You could connect to each subscriber individually of course, but if you're lucky that would mean hundreds or thousands of connections to manage. Federations standardise the interchange between the institution and the publisher and OpenAthens Cloud SP takes that to another level by putting all that behind one easy-to-code-for OIDC Provider that does all the hard work for you.