Matched betting has been around since bookmakers first began giving out bonus bets. It’s a common but relatively fringe form of arbitrage that is common in any country that allows online sports betting. You can read about it on Wikipedia here.
The premise is simple. We take a free bonus bet from one bookmaker (incentive to sign up), we could win or lose this and either get a nice risk free profit, or lose the free bet and break even, not a bad deal, but there is a better way.
Take for example a head to head match against Team A and Team B
If we take that free bonus bet and place a bet with the bookmaker that gave us the free bonus bet on Team A to win and then go to a competing bookmaker and place a bet on Team B to win, we will then be able to hedge our bonus bet, as we are only using real cash on the second bookmaker, and a free bonus bet on the first bookmaker, if we balance the real cash bet out on the second bookmaker we will will be able to ensure that no matter the result of Team A or Team B winning. We will win a profit on one of the bookmakers.
There is a little more nuance to the whole thing and the you need to know the correct amount to bet on the second bookmaker to ensure you profit either way, we use the simple matched betting calculator for this. There is also the issue of bookmakers requiring you to place a real bet after your first bonus bet before you can withdraw or sometimes to unlock your free bonus bet.
We handle this but replicating the first step again, place a dummy bet, bet Team A on the bookmaker with real cash and then balance the bet out on the second bookmaker with real cash ensuring that no matter the outcome again you will end up simply breaking even with this bet to unlock the free bonus.