It works OK, but it is very slow. I'm a tab hoarder and the addon showed nearly 800 duplicate tabs when I first downloaded it. I thought it would be a simple matter of hitting the "Close all duplicate tabs" button to get rid of the tabs, but nope! That crashed Firefox. Not only that, but when I restarted not a single duplicate tab had been dealt with...so either the process removes them all or it just crashes and removes none of them. Great.

So then I started removing the duplicates one by one, which is a time consuming process considering the addon lags for a good 2-3 seconds when closing each tab. Even attempting to quickly move through the list by simply going down and rapidly clicking the x's doesn't speed it up...it's just slow. I finally just made a mouse macro that clicked through them for me using a program called Mouse Recorder Premium...for those without such a program this part would have sucked!

So I pared the list down to 500. As an experiment I wanted to see if the addon would handle 500. Nope. Crashed again, but this time it also decided to crash Firefox every single time I tried to restart it as well...great! I disabled the addon after a few crashes and FF was able to start again. When I re-enabled the addon it was clear not a single tab had been removed and I still had 500.

Finally, I ran my macro a bit more and got it down to 150 (I actually wanted to stop at 250 and see if it would handle that but I got distract and the macro had already ran it down to 150 when I check it again...oh well). Now here's the reason why I didn't just rate this thing 1 star. It actually dealt with the 150 tabs pretty easily. Click the button and POOF they're gone. So I would say for the average user this addon will work quite the treat, but if you're someone like me that has a massive duplicate tab problem, well, expect to put in some work clicking those little x's and waiting.

As of October 2022 No longer functions at all. Removing.

Not a bad addon but could use a lot more functionality. For starters, it needs a whitelist for sites that are okay to duplicate, which is often necessary. Also, a simple "Close tab automatically" function really isn't the best way to handle a duplicate inadvertently being opened. For example, say you forget you've already got Google open and you type a search in the address bar (which I have set to auto open in a new tab). Rather than the new tab opening with the search I just typed, it switches to the old tab, with an old search in it, which is at first pretty disconcerting. In this case it makes more sense to close the old tab, not the new one, but again, maybe I actually do want them both open. There needs to be a white list. Did I say there needs to be a white list? There needs to be a white list.

RESPONSE TO DEVELOPER'S COMMENT: If you think I gave it two stars just for missing one feature, you didn't even bother to read the whole review. Two stars stands I now I don't even want to bother seeing if it's improved. You need to learn what reviews are for.

It could be better if there is an option to move the old tab to where the new tab would have been. Currently if you open hundreds of tabs and the old tab is in the front of the tabs, the tab bar will move all the way there, which is not good.

Reply:
I find out that if "On remaining tab" is set to "default tab behavior", the old tab will be moved to the new place, which is what I need.
Thanks for your response!

The problem is that there are cases when all duplicate tabs are closed without keeping neither of them or both
-auto-close on
-no filters
-keep newer tab (keep tab with HTTPS, keep pinned tab)
-scope: active window

The situation occurs when both tabs were loading simultaneous!

ok

Simple yet customize-able interface does the job.
Filters provide even more advanced options.

Feature request:
Don't show the badge and number when there is no duplicated tab.

Very good but has a bug:
By applying filters for ignoring both "hash part" and "search part" it will not work for duplicate tabs that have only "hash part".
For example for the following URLs one time apply only "ignore hash part filter" and another time apply both "ignore hash part filter" and "ignore search part filter".
https://www.mathworks.com/matlabcentral/answers/5802-perspective-transform-a-point-not-an-image#answer_8076
https://www.mathworks.com/matlabcentral/answers/5802-perspective-transform-a-point-not-an-image

Sooo good! Taming my 99 tabs with gdocs, things to read and random assortment!

This is super useful extension. I use it a lot.

Some suggestions for improvements:

* Allow possibility to "ignore" some open tab so it's not taken into consideration when checking for duplicates.
I had one or two situations when it would be useful (filters we not enough).

So for example when you have "duplicate tabs" list you could right click and choose "Ignore duplicate checking for this tab" (or some other better text) and this entry on "duplicate list" would get different colour or be in italic to indicate that we ignored this page. We could then click again and uncheck this option.
When tab is ignored then we don't see number that we have duplicate for it and "Close all duplicate tabs" won't close this tab.
* I have no idea what this "pin" do on different option sections ("Priority", "Filter", etc). Maybe have some hover over text that explain what it does
* Make this extension open source - this is of course you personal choice to keep it private. I just think it would be awesome and help improving this great extension even more.

This is really handy and has a good set of options for fitting into whatever way you like to browse. You should absolutely give this a try, and open the options panel if it doesn't suit you out-of-the-box.

The one extra thing I'd like to see is an option to have settings like "ignore path" apply to particular domains only -- I'd love to be able to open four articles from the same website but reliably collapse four instances of the same web-app.

Wer sehr viele Tabs offen hat, verliert schon gern mal den Überblick und es können Seiten doppelt geöffnet sein.
Mit diesem Addon ist damit Schluss. Danke ;-)