as far as anyone knows

and so far as anyone knows; to the best of one's knowledge

to the limits of anyone's knowledge. (The anyone can be replaced with a more specific noun or pronoun.) As far as anyone knows, this is the last of the great herds of buffalo. Far as I know, this is the best spot to sit. Q: Are the trains on time? A: To the best of my knowledge, all the trains are on time today.