How to determine what is considered a major or most popular browser

Frequently, I will read in a Request for Proposal (RFP) for Website Redesign a recurring requirement that goes something like this, “Website must be compatible with all major modern browsers.”

I’m happy to comply and confident that we can do it, but we need to have a specific standard of acceptance criteria to prove that we have performed the task and satisfied the requirement.  This begs two questions:

  1. What do you mean by compatible?
  2. What is a major modern browser?

Well, I’ve already defined cross-browser compliance and cross-browser compatibility in my blog post, “Cross browser compliance, how to make sites work across browsers.”  So, this blog post will discuss what the criteria for determining a “major modern browser.”

First of all, I take the data that the RFP was published because that is when the functional requirements were defined.  The reason this is important is because by the time the RFP goes out, proposals come in and are evaluated, a selection is made, and the actual website gets built; several months could go by.  In this period of time, old browsers could become obsolete and no longer supported while new browser come on the horizon.  It is critical that the scope of work and the standards for acceptance are frozen so we can work towards a fixed target.  It is, after all, quite a bit harder to hit a moving target.  So, if the RFP was dated in January but the website didn’t launch until October, then we will use January as the month to determine the “most popular browser” in January, not in October.

Second, I use a respectable and authoritative reference to statistically determine, based on a large data sample, what are the most popular browsers in the world for the month of the RFP.  In this case, I use “Browser Statistics: Most popular web browsers” by W3 Schools.  My criteria is that I will build for the top, most popular 96% of all major modern browsers identified by W3 Schools.  This means that if any web browser has less than 4% market share then I’m not building for it.  Again, the reference point is for the month that the RFP was published.  Take a look at the chart below:

You sill see that in January 2012, Firefox was the most popular browser at the time.  You will also see that Opera fell short of the 4% cutoff.  So, in the case of an RFP dated January 2012, I would ensure that the site is compatible for Internet Explorer, Firefox, Chrome, and Safari but not for Opera.

But, the plot thickens.  Which version of Internet Explorer, Firefox, Chrome, or Safari will I build for, ensure, guarantee, and warrant?  You have to dig deeper.  In this case, lets click on the Firefox link.

As you can see, when you drill down on Firefox, you realize that in January, the most popular version of Firefox was FF9.

You will also notice that FF11, FF10, and all Firefox versions prior to 3.6 fell under the 4% market share radar.  So, we could discount all of these versions and only build for Firefox versions FF9, FF8 because these were the “major modern browsers” at the time of the RFP.