Rated 4 out of 5 stars

Good addition.
But there is not enough to display the full link redirects. And copy part of the redirect chain.

This user has a previous review of this add-on.

It says what it does, and does what it says Rated 5 out of 5 stars

Too many extensions have great ambitions but work only a little bit.

This is a must have one. Many sites use abbreviated URLs on their pages, including popular ones like Facebook, and having Quo Vadis is a must if one wants to know where they will end up before getting there.

This is an excellent extension: straight forward, quick, and accurate.

This user has 2 previous reviews of this add-on.

Thanks a bunch!

Where is the source code? Rated 2 out of 5 stars

Works on some links, but breaks on roughly half short URLs.

Apart from that, this add-on is supposedly under the BSD license, implying its source code should be available somewhere. However, I can't find any mention to a source repository neither here nor on the developer's website.

Without this source, it is hard to assess the security risks of using this add-on (are my links sent to a third party?), and impossible to continue developing this add-on that the original developer visibly stopped.

Really?

Please supply information about the URLs you experienced as problematic.

EDIT:
Thank you for your feedback. This is what Quo Vadis? returned for the URL's you supplied:

--------------------------
https://t.co/MzaDzwFtm0
http://po.st/qWzYws
http://www.frenchweb.fr/5-start-up-francaises-de-liot-qui-vont-seduire-au-ces/221372
--------------------------
https://t.co/poEJoSYlGh
http://trib.al/P2Forxy
http://gu.com/p/4fjt4?CMP=twt_gu
http://www.theguardian.com/p/4fjt4?CMP=twt_gu
http://www.theguardian.com/commentisfree/2016/jan/08/kardashian-revenge-body?CMP=twt_gu
--------------------------
http://t.ted.com/OdoRlwx
http://t.ted.com/mC7J8YN
http://t.ted.com/2cYcdV3
http://www.ted.com/talks/gayle_tzemach_lemmon_meet_the_first_women_to_fight_on_the_front_lines_of_an_american_war
--------------------------
http://bit.ly/1S1JFrb
https://bitbucket.org/DjebbZ/bistromathique/
--------------------------

All final URLs were reached and all final URLs appeared as green text, indicating a HTTP response code 200 OK.
You quoted text from the source code file, so I guess you found it.
I wonder if you are using a the latest release of Quo Vadis?, being 1.4.0.1.
Are you using a release version of Firefox? Which one?
What platform are you using?

Rated 2 out of 5 stars

Why for referrer uses http://quovadis.basa.nl/?

upd:
@basa Really, why?.. But some strange people specially install addons to change referrer. Why do they do it?! Why does not everyone use your site for that?! Strange...

Why not?

Rated 1 out of 5 stars

This is exactly the tool I am looking for. Unfortunately does not seem to work (with Google search results). The tracking URLs were presented as-is in the right-click Quo Vadis popup instead of showing the target.

Dié resensie is oor 'n vorige weergawe van dié byvoeging (1.3.0.1-signed.1-signed). 

Thank you for your review.
Version 1.4.0 fixes the issue with Google (and DuckDuckGo) search results.