is it legal to use game explorer during a game???
See No Cheating or Computer Help
"You can NEVER use chess programs (Chessmaster, Fritz, etc) to analyze current ongoing games unless specifically permitted (such as a computer tournament, etc). The only type of computer assistance allowed is games databases for opening lines in Turn-based Chess and Vote Chess. You cannot receive ANY outside assistance on Live Chess games."
You are not limited to the chess.com game explorer.
During a Live Chess game, yes. During turn based it's allowed.
[Edit: this should have read "During a Live Chess game No...."]
[Edit2: Looks like I inherited this thread -- the original poster's inquiry was about the legality of using game explorer during a game]