Yes, both Miro and Slack offer a Free Trial.
Miro is designed for Large Enterprises, Medium Business and Small Business.
Slack is designed for Freelancers, Large Enterprises, Medium Business and Small Business.
Pricing for Miro Starts at $8/User/Month when Billed Yearly whereas for Slack Starts at $2.67/Month.
Some top alternatives to Miro includes Collaboard, Microsoft Whiteboard, WhiteboardFox, Conceptboard, MURAL, Lucidspark, Whimsical, Board, Zoom Whiteboard and Witeboard.
Some top alternatives to Slack includes Microsoft Teams, Glip, Google Chat, ChatWork, Dialog, Office Chat, imBee, Takle, SPACE Channel and Teamwork Chat.