Babel
JavaScript transpiler. Made ES6+ (arrow functions, destructuring, async/await) possible on older browsers by transpilation to ES5. Sebastian McKenzie, 2014. Standard 2015-2022 before SWC/esbuild took over for performance.
Plugin architecture: @babel/preset-env (auto-configure target browsers), @babel/preset-react (JSX), @babel/preset-typescript. Used by Webpack, Rollup, Parcel, Next.js (before Turbopack/SWC). Modern position: legacy fallback. Performance: slow vs SWC/esbuild (10-20x slower). React 17+ JSX transform was Babel-only initially, then replaced by SWC. Next.js + Vite moved away from Babel default ~2022. Babel maintains active development for ECMA stage-0 proposals + IE11-targeting (less relevant 2024+).