Chrome 42, released to the stable channel today, will take a big step toward pushing old browser plugins, including Java and Silverlight, off the Web. Those plugins use a 1990s-era API called NPAPI ("Netscape Plugin API") to extend the browser, and with Chrome 42, that API is now off by default.

For the time being, end users who really need to use these plugins will still be able to do so. The browser has a setting to re-enable the API, and administrators will be able to use Chrome's enterprise policies to enable it to do that. However, this is time limited: in September, Google plans to remove NPAPI support entirely. Chrome on Linux removed support in version 35, and its mobile browsers don't support it either.

Google is phasing out NPAPI because it says that it's a big cause of "hangs, crashes, security incidents, and code complexity." The company suggests that developers who were using NPAPI either use Web standards instead—the once Silverlight-dependent Netflix, for example, now uses Encrypted Media Extensions in conjunction with HTML5 video—or Google's own proprietary extension systems, such as the NaCl Native client.

These other extension mechanisms have been built to play better with Chrome's sandboxing system. Since 2010, Chrome's Flash support, for example, used an alternative Chrome API called Pepper/PPAPI, meaning that it is unaffected by today's change.

Safari and Firefox continue to support NPAPI. Internet Explorer did once, but dropped it in version 5.5 Service Pack 2.