In general this is a simple chat client using HTML, CSS, JavaScript, and just inter-iframe communication There is no server code on this project, just client. Basically you can put everything in a directory that will include the "site"+assets you'll build and open it locally on the browser. When a user opens the "site" all there is - is a "+" button. Every click on the "+" button adds an iframe to the page. This iframe is a chat client with the other iframes. Every iframe has a line you can write text in and press "send" to post. this post in shown on all iframes - like a chat room. All the iframes should communicate with the parent frame using postMessage. iframes should not communicate directly between them.
Extra features (Optional): Make it look nice iFrame windows should be draggable on the screen.