Yes, both Trello and Slab offer a Free Trial.
Trello is designed for Individuals, Freelancers, Large Enterprises, Medium Business and Small Business.
Slab is designed for Medium Business and Small Business.
Pricing for Trello Starts at $5/User/Month when Billed Yearly whereas for Slab Starts at $35/Month when Billed Yearly.
Some top alternatives to Trello includes ClickUp, Smartsheet, Miro, Process Street, Wrike, Notion, HubSpot CRM, Freshbooks, Jira, Basecamp, Zoho Projects, monday.com, Asana, Teamwork, ProjectManager.com, Microsoft Project, Worksuite, Trackboard, Quick Base, Todoist, Resource Guru and Height.
Some top alternatives to Slab includes Archbee, GitBook, Zoho Wiki, Drupal Wiki, LearnLode Enterprise, Matterial, TWiki, Wiki Valley, GoGoWorx and Kbee.