Yes, both Wikiful and GitBook offer a Free Trial.
Wikiful is designed for Individuals, Large Enterprises, Medium Business and Small Business.
GitBook is designed for Large Enterprises, Medium Business and Small Business.
Pricing for Wikiful Starts at $10/Month whereas for GitBook Starts at $6.40/User/Month when Billed Yearly.
Some top alternatives to Wikiful includes simplewiki, SlimWiki, GitBook, Zoho Wiki, Drupal Wiki, TWiki, Wiki.js, Wiki Valley, Microsoft Azure and You Need A Wiki.
Some top alternatives to GitBook includes Confluence, simplewiki, Zoho Wiki, Drupal Wiki, TWiki, Wiki Valley, MeisterNote, Team Wiki, Obsidian and Dokit.