Which technology does dblp use for searching the website?

dblp uses the CompleteSearch engine, developed by Hannah Bast (University of Freiburg, formerly MPII Saarbrücken). For years, Hannah has maintained a mirror site with extended search capabilities parallel to the dblp main website. Since 2015, the CompleteSearch engine is fully integrated in the dblp web system.
You can find publications about CompleteSearch here.