Yes, both Slack and Klenty offer a Free Trial.
Slack is designed for Freelancers, Large Enterprises, Medium Business and Small Business.
Klenty is designed for Large Enterprises, Medium Business and Small Business.
Pricing for Slack Starts at $2.67/Month whereas for Klenty Starts at $35/User/Month when Billed Yearly.
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 Klenty includes Apollo.io, AroundDeal, CrankWheel, ZoomInfo Engage, OutreachCRM, OutreachPlus, Outreach, ImagineSales, Use Outreach, Sales Booster by Leadspicker, OutReachly by 500apps, SalesHandy and SmartReach.io.