This is probably one of the most useful extensions I've come across. For online shopping and board forums, just open whatever products/topics you like and it will automatically close duplicated tabs instantly, saving so much time and headaches. You have to set them up a bit. If you don't know how to write regex, ask an AI. For example, with Amazon you can use ^(.*?(?:dp|gp\/product)\/) to compare only the ASIN in the URL.
A few quirks: some params it doesn't recognize; if you mass-open bookmarks from the same domain, because the tabs aren't loaded completely, it will mistakenly close them all but one if "auto close dupes" is on.
I also recommend the extension "ClearURLs". It removes almost all trailing trackers in an URL keeping it very clean.

My only objection is that tabs with the same title are considered duplicates (which is completely illogical) and this behavior cannot be disabled. Moreover, when I tried modifying the source code and installing the extension locally from file, it stopped detecting duplicates altogether even though the modification was straightforward and I'm pretty sure it should have just worked (I simply commented out the `else if (existingTitle === tab.title) {...}` block).