There are lots of ways to implement web applications in Perl. These will run on the server and send data to the browser (HTML, JavaScript, etc.), so they don't "run in the browser" in that sense; on the client side you can use JavaScript to make the website dynamic, if needed (for many simple applications it is not). For the Perl scripts on the server side, there are lots of modern frameworks you can use, see for example UP-TO-DATE Comparison of CGI Alternatives. Since it sounds like you're just getting started, you might want to check out Mojolicious::Lite and its tutorial.