Rated 1 out of 5 stars

Dear Ace Frahm, coders are human but this is an abondoned project. I tried to contact the author and he didn't reply me. HUNDREDS persons opened and updated tickets about the authentication, from months, without an answer.
Is this awful? Or is awful to leave persons with an extension used on daily basis not working from months?
And by the by, because I'm an awful person, I'm inclined to unpack the extension and fork it on github. At least the COMMUNITY could fix and carry on the project, seeing the lack of interest of the original author.

Rated 1 out of 5 stars

...what about a fork and (possibly) a bounty to add OAuth do Google Contacts? I'm not good with mozilla extensions or I would have done me myself...
gContactSync IS NOT a valid replacement. Eg. it DOES NOT works with multiple addressbooks and bug are not fixed. Google Contacts project deserve and need to be continued!