> For AI agents: the complete documentation index is available at /llms.txt, the full documentation bundle is available at /llms-full.txt.

# tools

Options for low-level tools.

## tools.bundlerChain [![tools.bundlerChain](https://assets.rspack.rs/rsbuild/rsbuild-logo.svg)tools.bundlerChain](https://rsbuild.rs/config/tools/bundler-chain)
[rspack-chain](https://github.com/rstackjs/rspack-chain) is a utility library for configuring Rspack. By using `rspack-chain`, you can more easily modify and extend Rspack configurations.



## tools.cssLoader [![tools.cssLoader](https://assets.rspack.rs/rsbuild/rsbuild-logo.svg)tools.cssLoader](https://rsbuild.rs/config/tools/css-loader)
Rsbuild uses [css-loader](https://github.com/webpack-contrib/css-loader) by default to handle CSS resources. You can modify the options of css-loader through `tools.cssLoader`.



## tools.lightningcssLoader [![tools.lightningcssLoader](https://assets.rspack.rs/rsbuild/rsbuild-logo.svg)tools.lightningcssLoader](https://rsbuild.rs/config/tools/lightningcss-loader)
You can set the options for [builtin:lightningcss-loader](https://rspack.rs/guide/features/builtin-lightningcss-loader) through `tools.lightningcssLoader`.

## tools.postcss [![tools.postcss](https://assets.rspack.rs/rsbuild/rsbuild-logo.svg)tools.postcss](https://rsbuild.rs/config/tools/postcss)
Rsbuild integrates PostCSS by default, you can configure [postcss-loader](https://github.com/webpack-contrib/postcss-loader) through `tools.postcss`.

## tools.rspack [![tools.rspack](https://assets.rspack.rs/rsbuild/rsbuild-logo.svg)tools.rspack](https://rsbuild.rs/config/tools/rspack)
`tools.rspack` is used to configure [Rspack](https://rspack.rs/config/index).

## tools.styleLoader [![tools.styleLoader](https://assets.rspack.rs/rsbuild/rsbuild-logo.svg)tools.styleLoader](https://rsbuild.rs/config/tools/style-loader)
The config of [style-loader](https://github.com/webpack-contrib/style-loader) can be set through `tools.styleLoader`.

## tools.swc [![tools.swc](https://assets.rspack.rs/rsbuild/rsbuild-logo.svg)tools.swc](https://rsbuild.rs/config/tools/swc)
You can set the options of [builtin:swc-loader](https://rspack.rs/guide/features/builtin-swc-loader) through `tools.swc`.