Mozilla Prism - Site-Specific Browser

Updated: April 17, 2009

The first time you hear about site-specific browsing, you raise a brow and wonder. What is this thing? And how is it different from the ... eh ... regular browsing. Site-specific browsing (SSB in short) is the concept of using a single instance of your web browser to visit a single website. In other words, when you launch the SSB, it will connect to only one specific site - and nothing more. In a nutshell, this is what Prism is all about. Sounds like a bad idea? Not all. Let me explain why.



You may have heard about this thing called cross-site scripting (XSS). You may have also heard about session hijacking, IFrames and other scary, geeky stuff, all of which are meant to tell you one thing: your browser cannot completely isolate websites from one another.

What really happens?

I'll try to explain in human terms. Let's call your browser a parent. Let's call all of the websites that you go to children. Now, when you are browsing the Internet with your favorite piece of software, be it Firefox, Opera or any other browser, you may have several windows or tabs open. Even though the websites may seem completely unrelated, they are all children of the same parent! All of these multiple sessions share the same browser resources. This means that if your browser has a problem, all of the sessions will suffer in one way or another.

If you're keen on security, you may have heard experts advising you to close all your browser sessions before connecting to secure websites, like banks, PayPal or others. This is precisely the reason: since all sub-processes running inside the browser share the same resources, you can't trust them.

With SSB, you get a clean, separate browser unit for each website. They run as completely unrelated processes, without any interaction. This means that even if you were browsing a potentially dangerous website trying to hijack information from other sessions, it is isolated and your "good" sessions are safe.


If your browser suffers an irrecoverable issue, it may have to crash. This means all websites you are connected to will crash, because they are all children of the same parent. In the SSB concept, each website is an independent, separate process. Should one of the website cause the browser window to suffer a seizure, it will close/crash, but all others will remain unaffected.

Minimalistic user interface

The SSB is all about content. Since you're viewing a single website, there's no need for bookmarks, navigation buttons or any other complex eye-diverting stuff that you get in regular browsers. You can focus on the content, without distractions.

This is what Prism is all about.

Prism is a new creation from Mozilla labs, the creators of the excellent Firefox browser, Thunderbird mail client and other goodies.

Prism is a simple browser hosting websites, or rather, web applications without the normal web browser interface. It is light, fast and robust. Prism allows you to launch websites directly from your desktop, without bothering with bookmarks and whatnot.

In a way, Prism integrates into your desktop, serving dedicated per-site weblets. I was skeptic about the concept until I tried Prism. The SSB idea is fresh and invigorating. It's another step in the direction of future browsing, where the classic role of the desktop is erased as computer usages goes more and more webby.

Let's see Prism in action!

Prism works both for Windows and Linux, so you can take your pick. In this short review, I'm using screenshots taken on Ubuntu, but the idea remains the same. In Linux, you can find Prism in most repositories. In Windows, the download is located on this page, under Getting Started with Prism.

Once installed, you can begin using Prism.

Create web app

It's very simple. Input the URL, give it a name, create a shortcut on the desktop and you're done. That's it. Create as many apps as you want, bearing in mind there's only so much desktop space, of course.


And when you launch the applications, you'll get the minimalistic SSB:

Web app

As you can see, there's nothing fancy about what you see - except the website, that is.

Firefox extension

However, manually creating apps for each website you like can be tedious. Luckily, you have a Firefox extension available, called Refractor (or Prism for Firefox), which allows you to do the same, from within the browser.

Firefox addon convert


Alongside Ubiquity, Prism seems another fine candidate for the future Internet. They both blur the distinction between desktop and web. If you're an old-timer, you may instinctively flinch from "Web 2.0" stuff, because you don't like the bells and whistles. No need to do that with Prism. If anything, Prism is spartan and glitter-free. It's a clean, lean, practical utility. What more, it can add to the security and stability of your browsing.

You don't have to convert every single site to an app, but the important ones, the one you wish isolated and to keep running even when others crash, you may want to use with Prism. I warmly suggest you try Prism. You won't be disappointed.