Не устанавливайте! Синхронизация мало того, что работает с глюками, так тут еще и КВОТА установлена!
Денег, им нужно ТОЛЬКО денег ...

whork proprely with ff et opera, no problem for me, great addon, continue!!

Before without imposing curves of funuts and payment, it was much better

Not works in Firefox under Linux

I had originally said "I cannot add this to Firefox ESR 52.4.1 (32-bit). I get the error 'this add-on could not be installed because it appears to be corrupt.'" I was able to find a solution at http://forums.mozillazine.org/viewtopic.php?p=14774300#p14774300: "
You will need to temporarily remove the config-prefs.js or autoconfig.js files to be able to install some add-ons (remove them with FX closed). Once the add-on is installed, put the file back to continue using the add-ons." I hope this helps someone.

Update: I've now used this for a few weeks, and so far, no complaints. After the initial installation issue, it was easy to use. I'll give it another month, and then will definitely make a contribution to support its further development. I should note that I had no problems installing it in Firefox ESR 52.4.1 (32-bit) on my workstation in my office.