Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
Now UI Kit - A beautiful Bootstrap 4 UI kit. Yours free.
Do by InVision - The world's most versatile to-do app UI kit for PS & Sketch
Module 02: Layouts - Professional toolkit for UI/UX design
TickTick - TickTickis a cross-platform to-do list app & task manager helps you to get all things done and make life well organized.
Startup Toolkit - Interactive how-to guides to launch your startup