Yes, both Slack and productboard offer a Free Trial.
Slack is designed for Freelancers, Large Enterprises, Medium Business and Small Business.
productboard is designed for Individuals, Large Enterprises, Medium Business and Small Business.
Pricing for Slack Starts at $2.67/Month whereas for productboard Starts at $20/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 productboard includes Aha!, Roadmunk, ProdPad, ProductPlan, Jira, Productroad, ProductFlare, Next Please, airfocus and IdeaPlan.