Joplin

Joplin is an open-source note-taking and to-do app that stores notes in Markdown format and organizes them into notebooks with tags. It includes OCR-powered search that finds text inside PDFs and images, supports code blocks, tables, and math expressions, and offers both a Markdown editor and a Rich Text editor. Joplin is offline-first, meaning all data is stored locally and remains fully accessible without an internet connection, with end-to-end encrypted sync available through Joplin Cloud, Nextcloud, Dropbox, OneDrive, or a self-hosted server.

The core app is completely free across Windows, macOS, Linux, iOS, and Android, and its source code is publicly available on GitHub. Joplin Cloud is an optional paid hosting service that adds features like notebook sharing, publishing notes to the web, a web app, and email-to-note, with plans ranging from a low-cost Basic tier up to Teams and self-hosted Business options. A browser extension for web clipping and a large plugin library round out the ecosystem.