Siemens
Yes, both Zendesk Support and Slack offer a Free Trial.
Zendesk Support is designed for Large Enterprises, Medium Business and Small Business.
Slack is designed for Freelancers, Large Enterprises, Medium Business and Small Business.
Pricing for Zendesk Support Starts at $19/user/month when yearly whereas for Slack Starts at $2.67/Month.
Some top alternatives to Zendesk Support includes Zoho Desk, ManageEngine ServiceDesk Plus, Deskero, Support Hub, HelpDesk, Desky, Help Scout, Salesforce Service Cloud, ReadyDesk, Sitehelpdesk, HESK and BoldDesk.
Some top alternatives to Slack includes Microsoft Teams, Glip, Google Chat, ChatWork, Dialog, Office Chat, imBee, Takle, SPACE Channel and Teamwork Chat.