Calculating molar masses quickly and online

Although I’m well aware and used to the fact that you can find anything on Internet, sometimes it still amazes me. Remember the time when you needed to fetch a periodic table of the chemical elements plus (optionally) a calculator to get a molar mass? Then came pieces of software that did it for you, but you still needed to fetch the software. Now, you can find the stuff anywhere on Internet, like at convertunits.com, where you can calculate the molar mass of TNT as easily as you can get the molar mass of potassium. I personally found it when trying to compare the molar mass of sodium salt (58.44 g/mol) vs potassium salt (74.55 g/mol), which is the thing used in salt substitutes like LoSalt.