Campfire Building a series bible with characters, places and lore. Free $0/mo; unlimited plan shown at $12/mo (from $19)
Notion Release calendars, series bibles and marketing trackers. Free $0; Plus $10/seat/mo; Business $20/seat/mo; Enterprise contact
Obsidian A private, linkable series bible stored as plain files. App free; Sync $4/mo annually ($5 monthly); Publish $8/site/mo annually; Commercial $50/user/yr
World Anvil Deep fantasy/sci-fi worldbuilding with maps and histories. Free tier; paid Master, Grandmaster and Sage tiers plus lifetime options (prices require login to view)