Thirteen people have pleaded guilty to disabling Paypal's servers in an attack US authorities say was orchestrated by hacking collective Anonymous.
The defendants acknowledged taking part in protests organized by Anonymous in December 2010 against Paypal, after the payment site cut ties to Wikileaks.
By pleading guilty, they will be hit with minor misdemeanour charges, as long as they stay out of trouble.
Paypal had urged leniency by prosecutors.
Lawyers for the defendants had argued that they were taking part in protests that should be protected by the US Constitution - specifically the First Amendment that guarantees free speech.
However, the US Department of Justice accused them of intentionally damaging a protected computer.
Paypal, which is owned by eBay, said it received attacks from thousands of computers during the 2010 protest.
Anonymous termed the attacks "Operation Paycheck" and targeted not just Paypal, but also larger credit card firms like Mastercard and Visa.
The targeted firms had stopped processing payments to Wikileaks, the anti-secrecy site, in the wake of the publication of 700,000 classified US documents and diplomatic cables.