Bootstrap published its first v6 alpha on October 8. CoreUI v6 followed with its first alpha two weeks later. CoreUI has been built on Bootstrap from the start, so the obvious question is how close the two v6 lines are.

The short answer: as close as we could make them, with a list of deliberate exceptions. For every file we share with Bootstrap we follow one rule. Class names, CSS custom properties, options, events and public methods stay the same as in Bootstrap wherever we can manage it, so moving from one to the other does not mean rewriting markup. The code behind those names is a separate question. Where we can do better than Bootstrap without changing a name, we do. Where following Bootstrap would cost our users a migration step that buys them nothing, we don’t.

This post goes through all three cases: what we took, what we left out, and where we kept the name but changed what is behind it.