I have been looking for an SSO application to handle authentication for multiple microservices but haven't been able to find anything that fits the description.

I have been looking for an SSO application to handle authentication for multiple microservices but haven't been able to find anything that fits the description. I was thinking about developing my own, but most of my time is spent on developing the services, and it's becoming pretty redundant to develop an auth system for each of them and it's pain to use if you need even two of them. Can anyone recommend something?