The test on this page aims to detect the browser extensions installed in your browser. You can learn more about the detection technique below.
Contrary to browser plugins, there is no JS browser API to obtain the list of installed browser extensions. The only way to detect browser extensions is to test the presence of certain files (web accessible resources) linked to the browser extensions. Thus, the presence of a file linked to an extension indicates the presence of the associated browser extension.
Because of the nature of the test (file probing instead of direct access through an API) the list of browser extensions detected on this page is not exhaustive. It only checks for the presence of popular browser extensions. I plan to add more extensions to the test in the future.
Yes, there are other ways to detect browser extensions. For example, certain browser extensions modifies the HTML DOM and define global variables in the JavaScript execution environment. Thus, it is possible to detect the presence of these extensions by checking the state of the HTML DOM and the JavaScript execution environment to detect side effects linked to specific browser extensions.
Yes, browser extension detection can be used for fingerprinting purposes as discussed in this research paper. The presence of a browser extension tends to make the fingerprint more unique since different users have different browser extensions installed. Moreover, the list of browser extensions installed in a browser is relatively stable over time, which makes it a good fingerprinting signal.