Obsidian

Obsidian is a note-taking app that works with plain Markdown files stored on your own device. It suits people who want to link ideas, keep notes for the long term and own their data.

Obsidian lets you write and organize notes as ordinary text files in a folder you choose. Notes can link to each other, and the app shows those links as a graph, so you can see how ideas connect over time. Because the files stay on your computer, you can open them quickly and keep working without an internet connection.

• Plain Markdown files in open formats
• Linked notes with a graph view
• Offline access to your whole library
• Community plugins and themes
• Optional paid sync and publishing

Obsidian suits writers, students, researchers and anyone who builds a personal knowledge base. It also fits people who prefer to keep their notes private and easy to move to another app later.

The core app is free to download and use, and the site describes it as free without limits. Sync and Publish are paid add-ons. Because notes are ordinary local files, you will need your own backup routine if you do not use the paid sync service. Plugins and themes come from the community, so quality varies from one to another.