Keypirinha - A lightning fast and flexible keystroke launcher for Windows. No installation required (portable).
Synapse - Synapse is a semantic launcher written in Vala that you can use to start applications as well as find and access relevant documents and files by making use of the Zeitgeist engine.
Listary - Listary is a revolutionary search utility for Windows
DockbarX - DockbarX is a standalone dock that groups and launches applications.
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.
Gnome-Pie - Gnome-Pie is a circular application launcher for Linux.