Yes, both Slack and Alterra offer a Free Trial.
Slack is designed for Freelancers, Large Enterprises, Medium Business and Small Business.
Alterra is designed for Large Enterprises, Medium Business and Small Business.
The starting price of Slack begins at $2.67/Month, while pricing details for Alterra are unavailable.
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 Alterra includes Quickchat, Conversational AI Bot, KODA Bots, InsiteBot and Tiledesk.