That 
What if the truth about humanity's past was hidden in plain sight—embedded in the source code of forgotten websites? When digital archivist Alex Chen receives a posthumous package from his former mentor Leo Kesey—dead for fourteen years—he discovers an impossible trail. Leo, a brilliant but paranoid web designer, claimed to have detected a SETI signal proving humanity existed before. A previous civilization, 47,000 years ago, that survived a near-extinction event and left one message: "Who survives, remember us." Everyone thought Leo was insane. His death in 2010 was ruled suicide. His evidence was destroyed.
I have a bias with the first digital agency I cut my teeth at, 2Advanced, being mentioned multiple times in the book but that aside it was a fun & easy read.
Definitely made me nostalgic for the early web and the fun things we use to do.