webpack is the heavyweight app bundler with a vast loader/plugin ecosystem; Rollup is leaner and favored for tree-shaken library output.
webpack is a mature, highly configurable bundler built for complex applications, with loaders, code-splitting, and a huge plugin ecosystem. Rollup focuses on clean, tree-shaken output and is the common choice for publishing libraries.
webpack
Rollup
Best for
Complex apps
Libraries, lean output
Config complexity
Higher
Lower
Tree-shaking
Good
Excellent
Plugin/loader ecosystem
Largest
Large, mature
Code-splitting
Mature, flexible
Supported
In CI
webpack handles complex application builds - many entry points, advanced code-splitting, and loaders for every asset type - at the cost of heavier config and slower builds. Rollup produces smaller, well tree-shaken bundles with simpler config, which is why it is the go-to for libraries (and the engine behind Vite's production builds). Choose by output target: app vs library.
Speed it up
Cache the build and dependencies keyed on your lockfile, and use persistent caching where supported. Both run on CI runners; faster managed runners cut the wall-clock time of heavy webpack builds.
Benchmark on your repository before choosing
Build-tool benchmarks published by vendors use repositories chosen to show a difference. Yours is the only one that matters, and both a cold and a warm measurement are needed because CI mostly runs cold.
Terminal
# cold: no cache, the CI condition
rm -rf node_modules/.cache dist && time <tool> build
# warm: the local development condition
time <tool> build
# and the one people forget: incremental after a one-line change
echo "// touch" >> src/index.ts && time <tool> build
The verdict
Bundling a complex app with many asset types and split points: webpack. Publishing a library or wanting lean, tree-shaken output: Rollup. Many teams get Rollup's output automatically via Vite.
Frequently asked questions
webpack vs Rollup: Which Bundler for CI Builds?
webpack is a mature, highly configurable bundler built for complex applications, with loaders, code-splitting, and a huge plugin ecosystem. Rollup focuses on clean, tree-shaken output and is the common choice for publishing libraries.
In CI?
webpack handles complex application builds - many entry points, advanced code-splitting, and loaders for every asset type - at the cost of heavier config and slower builds. Rollup produces smaller, well tree-shaken bundles with simpler config, which is why it is the go-to for libraries (and the engine behind Vite's production builds).
Speed it up?
Cache the build and dependencies keyed on your lockfile, and use persistent caching where supported. Both run on CI runners; faster managed runners cut the wall-clock time of heavy webpack builds.
Which should I choose?
Bundling a complex app with many asset types and split points: webpack. Publishing a library or wanting lean, tree-shaken output: Rollup. Many teams get Rollup's output automatically via Vite.
