Yes, both Slack and EmbedFeed offer a Free Trial.
Slack is designed for Freelancers, Large Enterprises, Medium Business and Small Business.
EmbedFeed is designed for Large Enterprises, Small Business and Medium Business.
Pricing for Slack Starts at $2.67/Month whereas for EmbedFeed Starts at $29.00per 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 EmbedFeed includes and undefined.