What are the CMS for organizing events?

Question

CMS

Good afternoon, I need some kind of CMS for organizing events, which would have its own API. The response must be in JSON format.
Are there such CMS or plugins for CMS? Thank you.
PS
I looked towards Xenforo because of the abundance of plugins and the availability of APIs (bd API or XenAPI). I found the events plugin, but it does not output data in JSON format. :(