A method and system for filtering website content prevents undesirable words or phrases from appearing in website postings sent by website users. The invention intercepts all content submitted by the user, and processes the content before posting it on the website. Intercepted content is first processed through a blocking subroutine, which first calls a preprocessing subroutine and then calls a content breakdown subroutine. The content breakdown subroutine utilizes a recursive comparison subroutine to identify undesirable words or phrases against previously identified words or phrases stored in a database. Options may be set in the system to replace the inappropriate content with acceptable content and then post the message or block the message entirely. The user may or may not be notified that their message has been blocked or replaced. The program then calls a matching subroutine for further processing of the intercepted content.