Yes, both Slack and Filestage offer a Free Trial.
Slack is designed for Freelancers, Large Enterprises, Medium Business and Small Business.
Filestage is designed for Freelancers, Large Enterprises, Medium Business and Small Business.
Pricing for Slack Starts at $2.67/Month whereas for Filestage Starts at $19/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 Filestage includes PageProof, GoProof, Ziflow, ProofCafe, QuickReviewer, Workgroups DaVinci Proof, WebProof, Coment, MediaMarkup and Proofing.