Flit

Flit is a free window switcher for macOS 14 and later. Press a shortcut (Control–Space by default), type a short mnemonic such as ch for ChatGPT, and you’re there. For apps with several windows, a few letters of the title pick the right one.

It remembers your mnemonics, can launch apps it has seen before, and never sends window titles anywhere: everything stays on your Mac.