Yes, both Slack and Jira Service Desk offer a Free Trial.
Slack is designed for Freelancers, Large Enterprises, Medium Business and Small Business.
Jira Service Desk is designed for Large Enterprises, Medium Business and Small Business.
Pricing for Slack Starts at $2.67/Month whereas for Jira Service Desk Starts at $10One-Time Payment.
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 Jira Service Desk includes Freshservice, ManageEngine ServiceDesk Plus, SolarWinds Service Desk, Mint Service Desk, Symantec ServiceDesk, Freshdesk, HelpDesk, ReadyDesk, Milldesk, HESK, Scopedesk and GLPI.