There is often confusion regarding this search term. It is a standalone commercial/educational website. However, many developers have recreated similar open-source math games and hosted those on GitHub.io.
Some popular (though often taken down) URLs follow this pattern: https://[username].github.io/[repository-name]/ mathsframe github io full
There are repositories dedicated to compiling lists of educational HTML5 games. These lists often link to *.github.io domains where independent developers host math tools similar to MathsFrame. There is often confusion regarding this search term