Preact is an attempt to recreate the core value proposition of React … using as little code as possible, with first-class support for ES2015. Currently the library is around 3kb (minified & gzipped).
So you get a React-like developer API experience in 3kb of JavaScript — That is insane.
At the time of this writing Preact has 4,000+ stars on github. Checkout Jason, the creator of Preact, talking about the origins of it on the React30 podcast episode. If you like React, then you should definitely give Preact a go in your next project.