Obsidian

Obsidian is a note-taking app that helps you create and maintain a knowledge graph. It encourages non-linear thinking, allowing you to jump from one idea to another without any friction. You can make connections between notes easily, creating a wiki-style link between them. This makes it easy to navigate between notes and see how they are related.

One of the best things about Obsidian is that it gives you complete control over your data. All your notes are stored in a local folder of Markdown files, which means you own all your data. You can keep it secure and private, without having to worry about any third-party access.

The app also has a flexible plugin system that you can customize to your needs. You can enable the plugins that matter to you, such as the in-app PDF viewer or the audio player. Obsidian also allows you to embed multimedia files like images and audio using the ![[image.png]] syntax.

Overall, Obsidian is a great app for anyone who wants to organize their thoughts and ideas in a non-linear way. It is perfect for students, researchers, or anyone who needs to keep track of a lot of information.

It's free for personal and commercial use. Apart from this, there are optional add-on services:

• Sync ($5 per month, $48 per year): Allows sync across devices with end-to-end encryption and version history.
• Publish ($10 per month, $96 per year): Allows publishing to Obsidian Publish.

There are also optional licenses to help development:

• Catalyst ($25 one-time payment): Grants early access to beta versions of Obsidian, access to insider channels and community badges.
• Commercial ($50 per year): Originally required for commercial use, it's meant to support the development and becoming a featured organization.