Ask HN: Startup Idea Evaluation

I've been writing enterprise software for a while and at times I come across this problem of single-sign-on (aka cross domain auto logins) between client's different sites. I usually end up writing my own solution for almost all clients I had. That is because what's out there in the market is either too complex and overwhelming for the requirements or way too simple and not so enterprise class. My idea is to create sophisticated APIs that are tied to a cloud based solution to solve single-sign-on. The thing I am not sure is if there is a market out there and if enterprises would consider my solution at all?