Everything[0] by Voidtools as a Windows search replacement. It makes search practically instant.

Now that Windows search often fails to turn up even my most used files (what happened to Windows search? Was it intentionally nerfed?), Everything has become a necessity for me.

[0]: https://www.voidtools.com/

FSearch is an equivalent for Linux.

https://github.com/cboxdoerfer/fsearch