If you're using a JS library, there is a good chance it supports an "autocomplete" widget. These work by using some event (e.g., "keyup" or whatever) to automatically send an asynchronous request to the backend with the current state of the search bar. The response will be handled by your Perl application and should return a list of entries to populate the dropdown list. Conceptually, this is straigtforward. However if you choose when to query the list poorly (e.g., too early) then it can quickly become both a user experience issue and a potential resource spike issue on your server. So on the server side, you just need a trad request handler given a "search term" (state of the input field). On the client side is where you do all the fancy stuff. You can get fancy on the server side with caching and whatnot, but I'd focus on getting it right on the client side first. Note: I have a forever hobby website that I maintain that includes a custom search. I've resisted putting in autocomplete, mainly because all the interesting stuff required is on the front end and I prefer the interesting stuff to be on the back end. So I have thought about it, just never executed on it.