Btodo is a Blender add-on for jotting down and managing notes, todos and texts through Blender's built-in text editor. Its UI sits in the text editor's properties panel, where you can create, rename and tag text data-blocks. You can also attach custom notes and comments to individual objects in the scene, and everything is packed into the project's .blend file.
The add-on organizes work into categories, notes and tags. You can create and remove categories, add notes to each one, and add an existing text data-block as a new note. Tags can be created, removed and assigned to notes, letting you list notes by category or by tag. A 'check' parameter supports todo-like notes as a check-list, and you can move notes between categories, rename items and rearrange them.
Three tabs cover the main views: category view for adding, removing and filtering by category; tag view for managing tags and sorting by them; and object view for listing all notes added to the active object. These tabs are also unpacked in the scene and object properties, and each panel's visibility can be shown or hidden.