Geolocation City Lookup on Website

Hello, I have a landing page hosted by Convertri which is a Landing landing page hosted service. They don't offer, such a service. So I can add a variable, to my webpage and the city will show up where that variable is. There shouldn't be any delay showing the variable before the city.. There are some free services out there that will allow you to do an IP lookup and retrieve the city. (I have one script that works but there is a delay which shows the variable then the city). You should be able to show me a demo of a working script. Ideally using a free or affordable lookup service. Thank you