Yes, both Slack and Messagely offer a Free Trial.
Slack is designed for Freelancers, Large Enterprises, Medium Business and Small Business.
Messagely is designed for Large Enterprises, Medium Business and Small Business.
Pricing for Slack Starts at $2.67/Month whereas for Messagely Starts at $29/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 Messagely includes ZoomInfo Chat, LiveAgent, LiveChat, Crisp, Zendesk Chat, Zoho SalesIQ, Smartchat, JivoChat, LinkedChat, ChatFlow247 and Let's Connect.