The acquisition was announced today in a press release and on the blogs of both companies, but no financial details are currently available.
Piriform is a privately held company based in London, UK, founded back in 2004. The company's claim to fame is its CCleaner application, a very popular OS optimization utility with versions for Windows, Mac, and Android.
According to Piriform, CCleaner has over 130 million users on desktop and over 15 million users on mobile. In November 2016, Piriform announced that CCleaner had surpassed two billion downloads, making it one of the most popular pieces of software worldwide, with over 23 million downloads each month.
Avast Press Release: Avast acquires Piriform, maker of CCleaner