Microsoft says that web apps will now be capable of using protocol handlers. This feature comes with support for Windows, Linux, and Mac, and is available in other Chromium-based browsers as well.

Firefox 3 adds a bunch of nice features under the hood for software developers. Many of those features, including native JSON support and web-based protocol handlers, have been under heavy development ...

Microsoft has disabled the MSIX ms-appinstaller protocol handler exploited in malware attacks to install malicious apps directly from a website via a Windows AppX Installer spoofing vulnerability.