Trilium Notes - Trilium Notes is a hierarchical note taking application.
YouDict - YouTube dictionary to search words, expressions & names
Quick Code - Curated list of free online programming courses
vdNote - Share noteworthy moments from YouTube videos.
Google Keep - Capture notes, share them with others, and access them from your computer, phone or tablet. Free with a Google account.
you-tldr - Get the tldr of any YouTube video in seconds