Dave Sifry is an American software entrepreneur and blogosphere icon known most recently for founding Technorati, a leading blog search engine. He also lectures widely on wireless technology and policy, weblogs, and open source software.

Sifry grew up on Long Island, and learned to program on a Commodore PET. He decided that he would move to Silicon Valley and start a company when he was still a teen. After studying computer science at Johns Hopkins University, he worked for Mitsubishi.

Sifry cofounded Sputnik, a Wi-Fi gateway company, and Linuxcare.

He has been a founding member of the board of Linux International, and a technical advisor to the National Cybercrime Training Partnership for law enforcement.