Yes, both Plumm and LiveAgent offer a Free Trial.
Plumm is designed for Medium Business and Small Business.
LiveAgent is designed for Freelancers, Large Enterprises, Medium Business and Small Business.
Pricing for Plumm Starts at $7/User/Month whereas for LiveAgent Starts at $15/User/Month.
Some top alternatives to Plumm includes LiveAgent, Enchant, SupportChamp, DeskMoz, Zoho SalesIQ, ChatFlow247, Little SaaS Communication, Qualified, Our Shared Inbox, Workvivo, Commons and Sociocs.
Some top alternatives to LiveAgent includes Zendesk Support, Zoho Desk, Tidio Helpdesk, Freshservice, ManageEngine ServiceDesk Plus, Freshdesk, ClickDesk, HelpDesk, SysAid, Jitbit Helpdesk, Desky, Help Scout, LabiDesk, LiveChat, Zendesk Chat, LiveHelpNow and Little SaaS Communication.