Microbundle
Zero-configuration bundler for tiny modules
... the result runs in 95% of web browsers without needing to be transpiled. Specifically, it uses Babel's "bugfixes" mode (previously known as preset-modules) to target the set of browsers that support <script type="module"> - that allows syntax like async/await, tagged templates, arrow functions, destructured and rest parameters, etc. The result is generally smaller and faster to execute than the plain esm bundle.