One of the common questions we get from Salesforce customers is "What browsers do you support?"

Currently, we officially support the following browsers:

• Internet Explorer 6 (with the latest hotfixes applied)
• Internet Explorer 7 (with the latest hotfixes applied)
• Mozilla Firefox 2.0

Many people think all browsers are the same--if a page works in Firefox it will certainly work in Internet Explorer, right?

Unfortunately this is not the case.  Supporting different browsers can take significant development and testing time.  We even see in many cases where different "dot" releases of Internet Explorer will render the same page in Salesforce very differently.

Because we strive to spend our time and effort on feature development rather than supporting various browsers, we limit the type and versions of browsers that we officially support to the set listed above.

However, we track browser usage pretty closely, and what we see can be surprising.

We've found that the best metric to track browser usage is logins per browser--this gives us a very accurate representation of usage per browser.

In the graph on the left, you can see that Internet Explorer is far and away the most popular browser used by our customers today.  This has been true since salesforce.com's earliest days.

Although several years old now, IE6 still sees the most usage, with nearly 2 of every 3 users logging in to Salesforce using that browser.

IE7, which we started supporting soon after it was launched in October 2006, is second in usage with 21% of users.

Firefox rounds out the most popular browsers, with combined Firefox 1.x and 2.0.x usage of about 12%.

After Firefox, usage of other browsers drops off dramatically.  Nevertheless, we see that even unsupported browsers like Netscape and Safari, with well under 1% of all usage, represent thousands of logins in a typical month.

This type of information--which is also uniquely available only in on-demand platforms like ours--helps us track usage trends among customers and better allocate our resources for bug fixing and browser support.

We also review operating system usage--although frankly this is less important to us because approximately 98% of users logging in with a browser are on a Windows operating system.

Breaking down Windows usage, you can see in the graph on the left that Windows XP represents over 85% of all logins, followed by Windows 2000 and variants at about 11.5%, and finally Vista rolling up at just under 2%.  (Apparently our customers aren't upgrading quite as quickly as Microsoft would like!)

What stands out here is not the high XP usage--XP has been available since 2001 after all--but the large number of logins still  happening on older, unsupported, and insecure Windows platforms like Windows 2000 and NT.

On one hand, we are thrilled that customers can access our service from almost any PC anywhere:  an internet cafe in some obscure corner of the globe, or your mother-in-law's house in Topeka.  On the other hand...scary!

Here at salesforce.com, the goal of the User Experience team is to provide the most productive work environment for our customers.  That means not only worrying about how we design and deliver our features, but also worrying about what browsers our customers are using.

To that end, we recommend that customers always access our apps on the most functional and secure browser platforms available today. We strongly recommend Microsoft Internet Explorer 7 (don't forgot those hotfixes!), and Mozilla Firefox 2.x (auto-update is your friend!) to all of our customers who want the best user experience possible.

As for Apple Safari 3.0:  stay tuned, we (and Apple) are working on it....