The Swiss army knife of productivity apps. Notes, databases, kanban boards, wikis, calendars, all in one place. If you're juggling dozens of projects, tracking which wallet did what on which chain, managing airdrop deadlines and keeping notes on every protocol you've interacted with, Notion is how you stop losing track of everything. Free tier is generous enough for personal use. The templates community is massive so you don't have to build everything from scratch.