Sucrase is a fast, modern JavaScript and TypeScript compiler that offers near-instantaneous build times by focusing solely on syntax transformations. Unlike full type checkers, Sucrase removes TypeScript types and converts modern JavaScript syntax (like JSX, optional chaining, and nullish coalescing) into older, widely supported versions. This makes it ideal for development and environments where speed is crucial and detailed type checking is handled separately. Significantly faster than tools like Babel or tsc for quick iterations.