Trilium Notes is a free knowledge base that scales past 100,000 notes and never asks for a subscription
A note tree deep enough to hold your working life, running on your own machine.
Trilium arranges notes into an arbitrarily deep tree, and a single note can be cloned into several places at once, so one reference sits wherever you actually go looking for it. The project is AGPL-3.0, community maintained under TriliumNext after the original developer handed over the repository, and its README says it scales well in usability and performance upwards of 100,000 notes, with per-note encryption and optional syncing to a server you host yourself. Desktop builds cover Windows, macOS, and Linux, with browser access through a server install and separate community apps on Android and iOS. MakeUseOf's Jack Mitchell moved off Notion and built what the piece calls a Knowledge OS on it, and names the one place it loses: it arrives looking plain, and an appealing workspace takes theming and CSS of your own.
