Yes, both Slack and Trainual offer a Free Trial.
Slack is designed for Freelancers, Large Enterprises, Medium Business and Small Business.
Trainual is designed for Medium Business and Small Business.
Pricing for Slack Starts at $2.67/Month whereas for Trainual Starts at $249/month when 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 Trainual includes and undefined.