Launchy is a free and open-source muti-platform application launcher.

DocFetcher is an open source desktop search application that runs on Microsoft Windows, Mac OS X and Linux.

searx is a privacy-respecting, hackable metasearch engine.

Recoll is a desktop search tool that provides efficient full text search in a friendly GUI, with minimum technical sophistication and few mandatory external d…

grep is a command-line utility for searching plain-text data sets for lines that match a regular expression.

TagSpaces is an open source data manager and file navigator. It helps organize files on local drives by adding tags to files.

Google Desktop was a computer program with desktop search capabilities, created by Google for Linux, Apple Mac OS X, and Microsoft Windows systems.

XWiki is a free wiki software platform written in Java with a design emphasis on extensibility.

Catfish is a search GUI powered by locate and find behind the scenes, with autocompletion from Zeitgeist and locate.

Index Your Files is a windows search utility.