A no deposit bonus is exactly what it sounds like - an online sports betting bonus that does not require an initial deposit. Think of it as a trial bet at online betting sites. If a bettor's wager wins, they get to keep the winnings, subject to the agreed upon terms and conditions. If they don't, then there is no downside since players haven't put up their own money yet.
It's no surprise that a no deposit bonus is a truly-risk free online betting bonus that attracts bettors like bees to honey. After all, a no deposit bonus lets bettors go through the process of making a bet on the betting site of their choice, which will let them decide if the betting site is worth sticking to.
Given that bettors have all the upside and the bookmaker carries all the downside, no deposit bonuses are becoming rarer and rarer since it can be quite expensive for bookmakers to fund.
Some betting sites tend to offer more free bets or a betting deposit bonus rather than no deposit bonuses. If one is available, it can be gone quickly since it's usually available for a limited time or for a limited number of customers.