Trilium is a personal knowledge base tool. This allows you to write and
  manage your knowledge in a structured manner.
Main features
  - hierarchical (tree) structure of notes - notes can be easily nested as
    necessary without imposing any depth limitations
    
      - extension of tree structure in the form of note clones - note can belong
        to multiple parent notes - thus appearing in multiple places in the hierarchy
 
- strong encryption - selected notes can be protected with strong encryption
    with key derived from password
- web application to be deployed on your server, desktop application (build
    on Electron) and data synchronization between instances
- fast keyboard-based navigation between different notes using "Jump-to"
    and "Recent notes" dialogs
Homepage
Trilium project is maintained in GitHub repository where
  you can find up to date documentation, source code and you can file issues.