JavaScript in a web browser is mostly invisible, for better or worse. When my paid extension StopTheMadness is working, you mostly don't notice it, and that's the point. My good JavaScript in the extension prevents bad JavaScript in web pages from affecting users. The value of StopTheMadness is obvious when you install it and some annoying web behavior immediately stops. However, the ongoing value of the extension is less obvious, since it Just Works™, as the saying goes. This is not a worry for StopTheMadness customers, who seem quite happy according to feedback and reviews, but it is a worry for me as the developer of the extension, and a user. In fact it started as a personal project for my own use. It just works for me too, and it has for a long time, so the question is how can I market the extension if I can't explain to people what specific problems it solves? The irony is that my problems are already solved. I've often joked that I should randomly disable StopTheMadness to show people what they'd miss without it. (Don't worry, I won't actually do this!)
My new free Safari extension FindTheMadness also started as a personal project for my own use, but I've decided to release it to the public. My goal was to be able to browse the web and not just hope to passively notice bad JavaScript, but rather to actively find it. FindTheMadness detects when JavaScript on websites overrides the normal expected behavior of your mouse and keyboard. When this happens, FindTheMadness alerts you. By default, FindTheMadness displays prominent alerts in the web page, but it also provides the option to display warnings in the Safari Web Inspector Console instead, because alerts in the page can interfere with page navigation, and they can quickly get annoying, ironically even more annoying than the bad website behavior they're designed to detect. With either FindTheMadness option, the purpose is simply to make the invisible JavaScript visible. You may be astonished to discover how often you click what you think is a link on a page, but you're actually running JavaScript triggered by a click. Don't let your mouse cursor fool you: websites are trying to fool you!
For several reasons, StopTheMadness doesn't have a free trial, but the free FindTheMadness is the next best thing to a free trial. FindTheMadness can find cases where StopTheMadness might be useful. FindTheMadness doesn't cover every StopTheMadness feature; StopTheMadness is chock full of features, not all of which involve preventing website annoyances. FindTheMadness does cover many common cases of bad JavaScript, though. Even if you have no intention of buying StopTheMadness, you may find it informative, enlightening (frightening?), to run FindTheMadness a bit and expose the "invisible underbelly" of the web. (Please note that FindTheMadness and StopTheMadness should not be enabled simultaneously in Safari, because the JavaScript in StopTheMadness will inadvertently trigger alerts from FindTheMadness.)
You can download FindTheMadness now from my web site (supports macOS 10.13 and later, including 11.0). FindTheMadness is sandboxed, and it's also notarized by Apple, for what that's worth. I decided not to submit it to the Mac App Store, because I was skeptical whether App Store reviewers would appreciate the utility and marketing of the app. Make sure to move the app from the Downloads folder to the Applications folder before running it, because our old friend app translocation is still around and causes trouble for Safari extensions. (It was broken on Sierra, fixed on High Sierra and Mojave, broken again on Catalina, fixed again on Big Sur.)