
If you are willing to assume the risk, there is a side door that Google left ajar for developers to test out their extensions, which you can use to install extensions that aren't listed in the Chrome Web Store. Now, according to Google, "to protect you while you browse, Chrome only lets you use extensions that have been published on the Chrome Web Store."

Last year, you needed only to enable Developer mode before installing a CRX (Chrome extension) file. A few years ago, you could simply install an extension from a developer's site without any hassle. Google has, over the years, increased its restrictions for installing third-party Chrome extensions to help protect Chrome users from malicious code.
