In a bid to protect people from accidentally installing malware, Google is blocking Windows and Mac users from loading Chrome extensions not hosted on the official Chrome Web Store. The company first introduced this policy for Windows users in May last year, but left it open for people using the developer version of Chrome (a more experimental version of the browser that's updated more frequently) to install extensions from wherever they liked. This, says Google, led to problems, with hackers forcing people to use the developer version of the browser before tricking them into installing malware. "Affected users are left with malicious extensions running on a Chrome channel they did not choose," said extensions manager Jake Leichtling in a blog post.

developers can still install non-web store extensions — but only locally

Instead, the company is now blocking all non-Web Store extensions on all versions of Chrome, with the new rules coming into force for Windows users in May and Mac users in July. The policy mirrors Apple's tight control over the App Store, which will likely lead some users to complain that it makes Chrome less open. Google's reasoning is clear, though: the company says that since it introduced the ban on the installation of non-Web Store extensions last year, there was a 75 percent drop in customers' support requests for unwanted extensions. Google also says that Windows and Mac developers can still install their own non-Web Store extensions locally by enabling developer mode, adding: "If your extensions are currently hosted outside the Chrome Web Store you should migrate them to the Chrome Web Store as soon as possible."