MUI is designed from the ground up to be fast, small and developer friendly. By design it only includes the basic components you need to build a site that follows Google’s Material Design guidelines. Material Design css framework MUI is heavily influenced by Bootstrap, Polymer, and Ink as well as some of the popular Material Design frameworks (Materialize, Material-Bootstrap, Material UI). In some places creators of MUI reused code from other projects in order to package it into MUI in a developer-friendly way. To comply with other open-source licenses and to encourage developers to hack on MUI, the source code for MUI is open-source under an MIT license.