The search functionality of FrogFind is basically a custom wrapper for DuckDuckGo search, converting the results to extremely basic HTML that old browsers can read.
Old'aVista is a search engine focused on personal websites that used to be hosted on services like Geocities, Angelfire, AOL, Xoom and so on.
RetroSearch provides the ability to search the Web using DuckDuckGo with a custom scraper that loads the first page of results and allows you to browse pages in plain text. You can deploy it on your local network and access it from your old computer!
The Old Net is an attempt to restore vintage web browsing on vintage computers. It uses the Internet Archive: Wayback Machine API and a proxy that strips out any incompatible javascript and stitches together as many links as it can.