Notion

Notion replaced wikis, project managers, spreadsheets, and note-taking apps with a single tool that does all of them adequately — which turns out to be more valuable than four tools that each do one thing perfectly. Founded by Ivan Zhao, it hit 30 million users by 2023 and was valued at $10 billion. The template ecosystem is enormous: 10,000+ community templates cover everything from CRM to wedding planning. Notion AI (launched 2023) added GPT-powered writing and summarization. The app's flexibility is both its strength and weakness — it takes 20 hours to set up and 2 hours to love.