Question: I'm implementing a SAML 2.0 Service Provider and need to install a SAML 2.0 Identity Provider for testing. Given this need, the Identity Provider should ideally be free (or have a trial period) and be easy to set up and configure.

I'm looking for basic single sign on and single log out functionality.

I've tried Sun Opensso Enterprise. The price is right, but so far it's been a nightmare to configure. Also, its error messaging and logging leaves a lot to be desired and I'm often troubleshooting an issue that basically boils down to a misconfiguration or a counterintuitive default setting.

Answer: 
You can give a try to LemonLDAP::NG (<http://lemonldap-ng.org>)

It is packaged for most Linux distributions, so easy to install and to set up.
I have been struggling with testing SAML2 integration for a long time, and used OpenSSO. Since I discovered **OKTA** for testing applications <http://okta.com/> I haven't looked back. It is perfect, easy to use, and you can also create different users and send custom attributes back to the SP. 

**OpenSSO** is not nice. For start you have those ridiculous captchas which don't even make sense. SSOCircle does not allow you to send custom attributes, it does not allow you to use SHA-256 encryption either, for what I've seen. OpenSSO does not give you any help about error messages unless you pay for their **debug** functionality (which is probably poor given the rest of the application works poorly).