Yes, both Tettra and KnowledgeOwl offer a Free Trial.
Tettra is designed for Large Enterprises, Medium Business and Small Business.
KnowledgeOwl is designed for Large Enterprises, Medium Business and Small Business.
Pricing for Tettra Starts at $8.33/User/Month when Billed Yearly whereas for KnowledgeOwl Starts at $10,000/Year.
Some top alternatives to Tettra includes Zoho Wiki, KBPublisher, Drupal Wiki, TWiki, KnowledgeBase Manager Pro, Omnistar Kbase, Talisma KnowledgeBase, KnowledgeOwl, KnowledgeBase and ProProfs Knowledge Base.
Some top alternatives to KnowledgeOwl includes simplewiki, KBPublisher, SmartSupport, Drupal Wiki, Talisma KnowledgeBase, Microsoft Azure, HelpHub, GoGoWorx, KnowledgeBase and ProProfs Knowledge Base.