How does SWC reduce NestJS build times by 70%?

SWC (Speedy Web Compiler), a Rust-based TypeScript compiler, replaces slower tsc/webpack in NestJS CLI v11+, achieving 17x faster builds through parallel processing and no AST parsing overhead. NestJS defaults to SWC builder for nest build --watch, configurable in nest-cli.json with "builder": "swc" or object options like type-checking. Benchmarks show large apps compiling in seconds vs minutes; supports decorators, source maps, minification. Customize via .swcrc for ESM/CommonJS targets matching tsconfig. Integrates seamlessly with Nx/Turborepo for monorepos.

Example:

nest-cli.json Config:-

Code

// nest-cli.json
{
  "compilerOptions": {
    "builder": "swc",
    "typeCheck": true
  }
}
      

Build Commands:-

Code

nest build  # 45s → 2.5s
nest start --watch  # HMR ready