TapTalk.io - TapTalk.io is a complete in-app chat SDK and messaging API - Easy integration and customizeable.
Procore - Procore is the world's most widely used construction project management software. Easy to use, mobile platform with unlimited user licenses.
Lets Chat - Open source self-hosted chat app for small teams
Corecon - Corecon offers integrated estimating, project management, and job costing for small to medium-sized construction companies.
MongooseIM platform - The massively-scalable XMPPJabber mobile messaging platform, for mobile and web, by Erlang Solutions
BuilderTREND - Buildertrend is the #1 construction management software and construction app for home builders, remodelers, specialty contractors and commercial construction.