When comparing Zopim vs PHPBack, the Slant community recommends PHPBack for most people. In the question“What are the best user support & feedback services?” PHPBack is ranked 10th while Zopim is ranked 16th. The most important reason people chose PHPBack is:
It has been already translated to Spanish and they are adding support for more languages.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Provides a useful series of tutorials
Zopim has a youtube channel that provides tutorials on using the product, and customer service tips.
Pro Multi-language support
It has been already translated to Spanish and they are adding support for more languages.
Pro Easy setup
PHPBack is very easy to setup, all you need is a server with PHP5 and MySQL installed.
Pro Open Source
PHPBack is open source, uses GPLv3 license.
Cons
Con Not a complete user support service
Zopim does not have all the features you may expect from a User support software. It is owned by Zendesk, so it's recommended you combine the ticketing features of Zendesk with the live chat on Zopim.
Con Small community
PHPBack is fairly young (first stable version was releases in July 2015). Currently the community is small, which may make it more difficult to find help/support.
However, the developer is active on the github page and generally responds quickly.