Betfair started in around 2000 as a betting platform where the players set the odds and bet against each other. This ability to ‘back’ (bet on) or ‘lay’ (bet against) was the beginning of the dynamic sports trading marketplace that Betfair is today. Betfair is by far the largest and most liquid exchange with over 1.2 million active customers and has expanded to include a sportsbook, casino, poker arcade, bingo, pools and virtual sports. Betting Exchange commission is between 2% and 5% on winning bets. Hugely competitive odds.Get Your Bonus!