Be Focused Pro: Pomodoro timer for both mac and iOS. Also has sync, reporting, multiple tasks. Works pretty well and has no subscribing cost.
Dash (Mac/iOS), Zeal (Linux): Documentation browser for loads of stuff (programming languages, libraries, frameworks). Works pretty fast and very readable.
Quiver or SnippetsLab: Code snippet notebook with markdown notes. Store your most re-used code snippets with documentation.
Magnet: Linux desktop managers have magnetic corners and auto resizing, but macOS lacks this feature. To enable, use Magnet. Organize your windows pretty neatly and fit many stuff into a single desktop. Work dense.
I have some tools to add to this list:
This guy knows, the only one that i don't have is Dash in my mac.
Thanks! It's a valuable addition to the list.