Bitcoin generators are dangerous to use. These tools will either affect your computer system or they will just steal your bitcoins and other valuable information. Those looking for quick method of earning bitcoin usually happen to be victims to these scammers.
Many free mining website offering you free bitcoins mostly are scam. After earning the minimum required for payouts, they will either just send you a fake alert of your withdrawal with no payment to your bitcoin address or simply don't just payout.
Good earnings comes from good works, everything comes with a price so just choose carefully.