Why it matters: It’s no secret that tech companies with competing products aren’t averse to using dirty tricks to get ahead. According to a former Mozilla executive, it’s something Google has been doing for years: intentionally sabotaging Firefox to increase Chrome’s popularity.

Jonathan Nightingale, former General Manager and Vice President of the Firefox group at Mozilla, revealed all on Twitter over the weekend. He writes that Google was the company’s biggest partner during his eight years at Mozilla. “Our revenue share deal on search drove 90% of Mozilla’s income,” he tweeted. But Nightingale claims Google used underhand tactics to ensure Chrome stayed ahead of its rival.

Nightingale says that while Google’s individual workers believed both companies were on the same side, the organization itself didn't see things that way.

"Google Chrome ads started appearing next to Firefox search terms. Gmail & [Google] Docs started to experience selective performance issues and bugs on Firefox. Demo sites would falsely block Firefox as 'incompatible'," he said.

"All of this is stuff you're allowed to do to compete, of course. But we were still a search partner, so we'd say 'hey what gives?' And every time, they'd say, 'oops. That was accidental. We'll fix it in the next push in 2 weeks.'”

These so-called accidents happened hundreds of times, and Nightingale doesn’t believe Google is so incompetent as to keep making mistakes. Each time one of these issues arose, Firefox lost users to Chrome.

This isn’t the first time such accusations have appeared. Last year, Mozilla Program Manager Chris Peterson tweeted that Google had intentionally slowed down the YouTube loading performance of Firefox and Edge. The site had previously loaded faster than Chrome on these browser, but Google “switched to using a JavaScript library for YouTube that they knew wasn’t supported by Firefox,” writes ZDNet.

According to NetMarketShare, Chrome holds almost 68 percent of the browser market while Firefox has just over 9 percent.