I believe it's
Chances are you've heard of me,
Some call me an oracle.
Wikipedia's very well-known as a source of information.
I'm the savior late at night.
Wikipedia's often used as a source for research, especially by students who don't have the time to look up a proper reference.
Beware, not all that you see,
Is truth or fully right.
Wikipedia can be edited by anyone, so its information isn't always true
Search now, for what I may be,
Google and I are good pals.
Google searches for things on Wikipedia often give the Wikipedia page as one of the first search results.
No paper, I saved the tree.
Wikipedia's purely digital, not on paper.