Jon started Excel Campus in 2009 and has since turned it into one of the best Excel sites out there. Jon’s posts are so detailed and thorough that even if you’ve been using Excel for 20 years, you’ll probably still learn something new about a topic you thought you knew completely.
Purna Duggirala runs the very popular site Chandoo (which is his nickname). The site has existed since 2004 but he only began blogging about Excel in 2007. There are a ton of in depth articles covering every topic in Excel. There is so much here that it can sometimes feel disorganised and hard to find what you’re looking for.