Logseq is a knowledge-management and note-taking tool built around outlines and interconnected notes. It works with Markdown and Org-mode files, supports PDF annotation and task management, and offers a plugin API and themes. It is available as a desktop app, a web app and an iOS app, for individuals and teams who want a personal or shared knowledge base.
Logseq is open source under the AGPL-3.0 licence. The project lives in the logseq GitHub organisation, is developed by Logseq Inc. with contributors, and is funded through Open Collective. Notes are stored as plain-text files on the user's own device, so the tool is local-first and content stays under your control unless you choose to synchronise it elsewhere. For a European organisation, local storage, readable file formats and auditable source code reduce dependence on the developer and make it easy to keep working data on infrastructure you control.