"Since we don't store IP addresses or use tracking cookies, we've offered powerful privacy protection to our users since 2006," said Ixquick CEO Robert Beens.
"Our fans especially appreciate the fact that we are a Dutch company, which means we are not directly subject to the US Patriot Act. And of course, we have never participated in any program like PRISM."
The previous record of three million searches in one day was set three weeks earlier.
StartPage acts as a proxy for Google's search engine, obtaining results without exposing the end user to Google.
While this adds a layer of privacy (Ixquick was the first company to receive the European privacy seal), it does mean that the Google results are not tailored to reflect the user's search history. Whether that's a good or bad thing depends on your point of view.
Ixquick carries out a metasearch, submitting the same query to several search engines and highlighting the results that are highly ranked by multiple engines.
Ixquick also pioneered the default use of HTTPS connections for searching, and the company plans to launch StartMail, a private email service with strong encryption, later this year. Potential users are invited to sign up as beta testers.