Directory

Apple's built-in notes app for Mac, iPhone, iPad and iCloud.com with folders, tags, attachments, handwriting, shared notes and on-device search

Open-source, outliner-based knowledge base storing notes as local Markdown or Org-mode files with block references, queries and a graph view

Local-first Markdown note-taking app with bidirectional links, graph view and a large community plugin ecosystem; optional paid Sync and Publish

Apple's built-in visual automation app for macOS, iOS and iPadOS that chains app actions, scripts and system functions into runnable shortcuts

Minimal, high-speed VPN protocol and implementation built on modern cryptography, included in the Linux kernel and available on macOS, iOS, Windows, Android and BSD

Free, open-source reference manager with browser connectors, word-processor plugins, a PDF reader, group libraries and optional paid file storage