Stevenage appeared to be slipping to their first league defeat of the new term with just 10 minutes gone - Crewe striker Ajay Leitch-Smith netting twice in as many minutes.
However the hosts hit back through Luke Freeman in the 27th minute before Chuks Aneke saw red for a two-footed lunge after the break and Shroot pounced to seal a draw late on.
Crewe hit the front with just six minutes gone as Leitch-Smith stole a march on his marker at the far post to meet a low cross and fire high into the roof of the net.
And it was Leitch-Smith who made it two little more than a minute later, racing clear of Boro's back four to finish emphatically across keeper Chris Day.
Stevenage reduced the arrears when Freeman smashed home a vicious 25-yard drive while loanee Aneke was dismissed for an ugly two-footed lunge on Anthony Grant in the 73rd minute. And Shroot made him pay eight minutes later collecting on the turn and firing past the stricken Alan Martin.