A single, specific tool and an adjustable wrench are all you need to remove most crank arms from square taper or splined (Octalink, ISIS) cranksets. The most common threading used on those designs is 22 x 1mm, and that is what you find on the Park Tool CWP-7C Universal Crank Puller. This tool has tool ends on two sides that have a specifically sized rotating head on a pin with an o-ring that holds the end to the tool body. The smaller interface is for square taper bottom brackets, and the larger end is for the hollow, larger bore Octalink and ISIS models.

To use, you set up the end you want to use, then hand thread the tool threads into the threaded interface of the crank arm. Use care to thread cleanly, as most such cranks are made from aluminum alloy that is easily damaged. Once you hand thread as far as you can, use a wrench to increase pressure onto the bottom bracket spindle, which pushes the crank arm off. This is a great tool to have on hand for everyday mechanics and convenient for home use if you have older bikes or kids bikes with these interfaces.