Yes, both Slack and Proxyclick offer a Free Trial.
Slack is designed for Freelancers, Large Enterprises, Medium Business and Small Business.
Proxyclick is designed for Large Enterprises, Medium Business and Small Business.
Pricing for Slack Starts at $2.67/Month whereas for Proxyclick Starts at $100/Month.
Some top alternatives to Slack includes Microsoft Teams, Glip, Google Chat, ChatWork, Dialog, Office Chat, imBee, Takle, SPACE Channel and Teamwork Chat.
Some top alternatives to Proxyclick includes Vizitor, Visitdesk, Lobbytrack, Envoy Visitors, Veris, VisitUs, TDS Visitor, LobbyGuard, Vizmo and Spectra Visitor Management.