Zeplin has classic support with a chat from the website. It's working fine, and we're also getting the support needed when needed. However, Zeplin is very good at closing the incidents and moving on. It was a while ago we had a case with their support so that it might have improved since then.
Zeplin has been extremely well timed with updates and support tickets being answered. I have waited no longer than 3 hours in the worst case scenario. Plus, out of the years of use, I have only needed to contact support once!
Zeplin, from the company of the same name, is a platform supporting collaboration in application development by engineers and designers by providing an API with popular collaboration, development and prototyping tools and creating a space where productions can be shared and reviewed.