While there are certainly illegal online casinos that provide fixed games and steal from punters, these are thankfully in the minority. All of the casinos we recommend are licensed and offer fair games.
Licensed casinos are forced to abide by the strict rules and regulations enforced upon them by the gaming authorities. This included providing fair games, using encryption and securely storing player data. Gaming authorities routinely audit online betting sites to check they are following the regulations. If online casinos fail to follow these rules, they face fines and even criminal prosecution.