Keypirinha - A lightning fast and flexible keystroke launcher for Windows. No installation required (portable).
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
Alfred - Alfred is an award-winning app for macOS which boosts your efficiency with hotkeys, keywords, text expansion and more. Search your Mac and the web, and be more productive with custom actions to control your Mac.
Todo.txt - Track your tasks and projects in a plain text file, todo.txt. A todo.
Listary - Listary is a revolutionary search utility for Windows
EssentialPIM - EssentialPIM is a free Personal Information Manager that keeps up with the times and lets you manage appointments, tasks, notes, contacts, password entries and email messages across multiple devices and cloud applications.