Found out about this extension from a Book RIot article. Works flawlessly for me and my library system.

A great add-on that could be even greater if the library definitions one selects would also imply their inter-library loan systems. Colorado libraries use a system called "Prospector" that rummages through other systems in the state including university libraries, etc. If the Extension library definitions could somehow pull in the inter-library systems as well, that would make a great add-on even better! I'm pushing my luck here, but since there's an exhaustible list of libraries to choose from in the extension, perhaps a "nearest availability" option where, when a book isn't available from the chosen list then the next best/nearest availability option could be shown?

I was impressed when I learned of this extension, but when I started using it, WOW!!! I no longer use the library catalogs as this add-on gives me everything I need, faster and easier. Having cards for several libraries I used to have to search each one individually, but no more. Fantastic App! Wish it worked on mobile devices but having it on Firefox now is great!! Thanks for a Stellar product!

Fantastic app, does exactly what it's supposed to

This extension works flawlessly and is amazingly useful. Thanks to all who worked on bringing this tool to life.

This does exactly what is says it does and it's marvelous! Saves me a lot of time cross-checking all my libraries for a title before buying it.

Love, love, LOVE this extension! In the past, I had to search every library site before purchasing a book. Now all I have to do is view the Amazon page and I know if the book is available FOR FREE in a library. Thanks so much for this outstanding Add-on!

I love this extension. It shows up on both my LibraryThing page and my Amazon page and immediately lets me know what is available in my library system. So convenient!!

This is one of the best extensions in a while! This is very useful to make the most out of your library card!

I love it so much. What a fan-freaking-tastic firefox extension. I live in a big city and frequent two different library systems, it had them both and shows them all when I am looking at a book on Amazon. It has only ever worked basically perfect for me. Again, I love it.

Works great with my local libraries and hoopla. Saves time and money knowing that I might be able to read something for free from library before purchasing from Amazon.

Did not have my local library on the list but, as soon as I reported this, I had an immediate response and, within days, it was added! Fantastic support response and the extension works like a dream. Excellent!

This extension is something I told my wife I needed long ago. Our library loans out e-books as well as hardcopy and I still prefer hardcopy.

I used to open my local library catalog to look up authors I thought likely to be there before buying an e-book. I've found this add-on to be extremely helpful in reducing my catalog lookups for something that wasn't there.

Library Catalog searches are still troublesome. So having this plugin search that catalog for me is incredibly helpful.

Works fine, saved me money already! Customer support is very responsive. I requested addition of my most-used library and it was rapidly done!