For years, Malwarebytes earned a reputation as the "clean-up crew" of the internet. Users would run it after their primary antivirus failed to detect an infection. The company has since expanded its mission beyond simple malware removal:

While working as a technician in a computer repair shop in high school, Kleczynski developed RogueRemover to eliminate fake antivirus programs.

In the early 2000s, teenager was using his family's white Dell computer to play video games he had obtained through "nefarious" means. One of these downloads turned out to be a virus that infected the machine, causing performance issues and constant pop-ups. Fearing his parents' reaction to the broken computer, Marcin turned to online message boards for help.

He connected online with Bruce Harrison , a forum regular who shared his passion. Despite making $600,000 in their first year together, the two reportedly had not yet met in person.