"... guest post by Ray Villalobos. Ray is going to explore many of the different varietals of Markdown. ... which versions have which features to help you make an informed choice."
"Browserscope is a community-driven project for profiling web browsers. The goals are to foster innovation by tracking browser functionality and to be a resource for web developers."
You can compare two or three files and edit them in place (diffs update dynamically). You can compare two or three folders and launch file comparisons.