Here are the top FREE cross-browser testing tools to assure your website looks consistent across most common browsers. This list does not include sites or platforms with a limited free trial. Free testing across multiple browsers and older Internet Explorer versions is becoming harder to find. The downloadable testers are for Windows OS only.

Browser Sandbox

Free to use on Windows Desktops. Download and use Browser Sandbox to test Internet Explorer 6 – 11, Chrome, Firefox, Opera, and nightly and beta builds of Chromium Canary and Firefox Nightly.

Net Renderer

Net Renderer supports Internet Explorer 5.5 – 11.

BrowserShots

Supported browsers:
IE, Firefox, Google Chrome, Opera, Safari, Minefield, Netscape and many more browsers with all versions.

IE Tester

This is one I’ve been using for awhile now. Download IETester to test websites on IE 5.5, IE6, IE7, IE8 and IE9 preview browsers on Windows 7, Vista and XP operating systems.

Browserling

Live interactive cross-browser testing in 3-minute sessions on Windows 7 or Windows Vista for IE 10 & 11, Chrome, Firefox, Safari, and Opera.