Yes. Everyone gets the same 4×4 board each day, built on our server, and a new one arrives at midnight UTC. Your words are checked there too.
The board is drawn on our server from a secret daily seed, so nobody can work out tomorrow’s board from the page. Boards are redrawn until they hold plenty of words, including at least one long one.
When you finish, the server rebuilds that day’s board, checks each word you found and ranks the score it computes, not the one your browser claims. Set a display name to appear on the leaderboard.
See also How Word Hunt is scored. For tips, read the Word Hunt tips and strategy.