Is it legal to generate PSN card codes for free?

Sony's Terms of Service and User Agreement explicitly forbids cheating, hacking, fraud, reverse engineering its code, deceptive practices and using content or services without paying when it normally must be purchased. Thus, any method of adding funds to your account without legitimately obtaining the content violates its legal terms.

Sony has the right to terminate any account that might have violated its Terms of Service and User Agreement and take legal action against the account's owner. Some code generators may also be scams created to obtain personal information, take control of a user's account or distribute malicious code, according to Sony.