Rollup vs. Parcel vs. Webpack: Which is the Best Bundler? (2023)

The battle of the bundlers

Rollup vs. Parcel vs. Webpack: Which is the Best Bundler? (1)

Recently I was publishing a library to npm and I thought of experimenting with the bundler I was going to package my code in. While webpack has always been my standard choice, I decided to put it up against two other popular bundlers — Rollup and Parcel.

For those coming from a non-JavaScript background, a bundler is a tool that recursively follows all imports from the entry point of your app and bundles them up into a single file. Bundlers can also minify your files by removing unnecessary white spaces, new lines, comments, and block delimiters without affecting their functionality.

Let’s try to understand this through a simple code snippet:

var test = [];
for (var i = 0; i < 100; i++) {
test[i] = i;

We just created an array called test and initialised its members till 100. The minified version of this code will look somewhat like this:

for(var a=[i=0];++i<20;a[i]=i);

Fewer characters and lines. You might say the code is not readable, but who cares? You bundle your code once it’s ready, and minified code is easy to fetch and interpret for the browser.

It must be now easy for you to guess the importance of a bundler, right?

Suppose your code is not bundled and hosted as a package of multiple files on the server. For the import of each of these files to make your code run, the browser has to send a separate HTTP request to the server. The efficiency of this transmission is directly proportional to the number and size of the files being requested. In the case of large apps such as Facebook, this can lead to disastrous performance and UX.

However, the performance of the app substantially improves with a bundler on board as now the browser only has to request a single file to display your app to the user. Moreover, fetching a minified file weighing a few KBs is faster than the actual file, which might run into MBs, resulting in improved load time of the app.

(Video) Webpack, Rollup and Parcel Compared

Sure you can, but when working with huge codebases, minifying the app manually isn’t a scalable solution. Let the bundler do it for you!

Making the right choice of a bundler from the many available can be life-changing for your app, depending on the use case. Coming back to the experiment I was talking of in the beginning: I thought of sharing with you my findings on how webpack, Rollup, and Parcel fared on some important requirements a developer would have.

Configuration of the bundler

Parcel wins here as it doesn’t require a config file at all. Just install Parcel and run Parcel build, and it will do everything for you out of the box.

webpack and Rollup both require a config file specifying entry, output, loaders, plugins, transformations, etc. However, there’s a slight difference:

  • Rollup has node polyfills for import/export, but webpack doesn’t.
  • Rollup has support for relative paths in config, but webpack doesn’t — which is why you use path.resolve or path.join.

webpack config can get complex, but it provides extensive support for third-party imports, images, CSS preprocessors, and whatnot.

I had a hard time using Rollup for bundling my app that used axios, a very commonly used library for making HTTP requests — not just axios, but for other third-party integrations too. I had to research a lot and try installing many Rollup plugins before attaining victory — at the cost of dropping some imports.

Dead code elimination

Dead code elimination, or Tree shaking, as it’s often called, is very important to achieve the optimum bundle size and hence app performance.

Parcel emerged as the winner here. Parcel supports tree shaking for both ES6 and CommonJS modules. This is revolutionary since most of the code in libraries on npm still uses CommonJS.

Most of the work Parcel does when tree shaking is also done in parallel through multicore processing using numerous worker processes and is also cached on the file system. This means that builds are still fast and rebuilds are like blazingly fast.

Rollup comes second in the race. Right out of the box, it statically analyzes the code you are importing and will exclude anything that isn’t actually used. This saves you from writing more lines into your config, adding extra dependencies and bloating the size of your app.

(Video) Module Bundlers Explained... Webpack, Rollup, Parcel, and Snowpack

webpack requires some manual effort to enable tree-shaking:

  • Use ES6 syntax (i.e. import and export).
  • Set the SideEffects flag in your package.json.
  • Include a minifier that supports dead code removal (eg: UglifyJSPlugin).

Rollup and webpack have focussed more on tree shaking for ES6 since it is much easier to statically analyze, but in order to truly make a big impact, we need to analyze CommonJS dependencies as well, for which they both require plugins to be imported.

However, given the fact that JavaScript is dynamic, almost every construct in the language can be altered at runtime in impossible to predict ways.

Practically, this means that an entity such as a class, which is imported as one reference, cannot be statically analyzed to remove members (both static and instance) that are not used. So rather than overly relying on the bundler to do it for you, it will be a good practice to visualize your components before you code and analyze them afterwards to get the best results.

Code splitting

As your app grows, your bundle size will grow too, more so with third-party imports. The load time of your app is directly proportional to its bundle size.

Code splitting helps the browser lazy-load just the things that are needed to get the app running, dramatically improving the performance and UX.

webpack emerges the winner in this aspect, with minimal work and faster load time. It provides three approaches to enable code splitting available in webpack:

  • Define entry points — Manually split code using entry configuration.
  • Use the CommonsChunkPlugin to de-dupe and split chunks.
  • Dynamic imports — use inline function calls within modules.

During code splitting by Rollup, your code-split chunks themselves are standard ES modules that use the browser’s built-in module loader without any additional overhead, while still getting the full benefit of Rollup’s tree-shaking feature. For browsers that don’t yet support ES modules, you can also use SystemJS or any AMD loader. It is completely automated and results in zero code duplication.

Parcel supports zero-configuration code splitting. Here code splitting is controlled by use of the dynamic import() function syntax proposal, which works like a normal import statement or require function, but returns a Promise. This means that the module is loaded asynchronously.

It was tempting to favour Rollup and Parcel over webpack for code splitting, but both of them have only recently introduced this feature and some issues have also been reported. So it’s safe to stick with the good old webpack.

One compelling fact I noticed was that for the same code with code splitting enabled, the build time was least with webpack, followed by Rollup, and lastly Parcel.

(Video) Module Bundler in JavaScript | Webpack vs Rollup vs Parcel

Live reload

During development, it’s great if your app gets updated with fresh code that you write, instead of manually refreshing it to see the changes. A bundler with live reload capability does that refreshing for you.

Bundlers provide you with a run-time environment in addition to other utilities essential for debugging and development, in the form of a development server.

Parcel has been very thoughtful by having a development server built in, which will automatically rebuild your app as you change files. But there are issues associated with it when using HTTP logging, Hooks, and middleware.

When using Rollup, we need to install and configurerollup-plugin-serve, which will provide us with live reload functionality. However, it needs another plugin, rollup-plugin-livereload, to work. That means it’s not an independent plugin and comes with an extra dependency to run.

With webpack, you just need to add one plugin, called webpack-dev-server, which provides a simple development server with live reload functionality turned on by default. What’s better? You can use Hooks to do something after the dev server is up and running, add middleware, and also specify the file to serve when we run the dev server. This customisability of webpack trumps Rollup and Parcel.

Hot module replacement

Hot module replacement (HMR) improves the development experience by automatically updating modules in the browser at run time without needing a whole page refresh. You can retain the application state as you make small changes in your code.

You might ask how HMR is different from live reload.

Well, live reloading reloads the entire app when a file changes. For example, if you were five levels deep into your app navigation and saved a change, live reloading would restart the app altogether and load it back to the landing/initial route.

Hot reloading, on the other hand, only refreshes the files that were changed while still maintaining the state of the app. For example, if you were five levels deep into your app navigation and saved a CSS change, the state would not change: You’d still be on the same page, but the new styles would be visible.

webpack has its own web server, called the webpack-dev-server, through which it supports HMR. It can be used in development as a live reload replacement.

While Parcel already had built-in support for hot module replacement, Rollup released a plugin rollup-plugin-hotreload last month to support hot reload.

(Video) Vite is The New Webpack and Create-React-App killer!

As this capability is fairly new in bundlers like Rollup and Parcel, I still choose webpack as the safe bet for I don’t want to run into avoidable issues during development.

Module transformers

Bundlers generally know only how to read JS files. Transformers are essentially teachers who teach the bundler how to process files other than JS and add them to your app’s dependency graph and bundle.

Rollup vs. Parcel vs. Webpack: Which is the Best Bundler? (2)

For example, in the image above, you can see a webpack config having an instruction on how to read CSS between lines 13 to 15. It basically says, “Hey webpack, whenever you encounter a file that is resolved as .css, use css-loader imported above to read it and export it as a string.” Similarly, an HTML loader will tell webpack how to read the .html files it encounters in your app and export them as strings in your bundle.

Parcel handles the transformation process very smartly. Unlike Rollup and webpack, which need you to specify file types to transform, install and configure, plugins to transform them, Parcel provides built-in support for many common transforms and transpilers.

Parcel automatically runs the appropriate transformer when it finds a configuration file such as.babelrc, .postcssrc, .posthtml, etc. in a module. In addition to any transforms specified in .babelrc, Parcel always uses Babel on all modules to compile modern JavaScript into a form supported by browsers.

Following is the crux of the findings from my experiment:

Building a basic app and want to get it up and running quickly? Use Parcel.

Building a library with minimal third-party imports? Use Rollup.

Building a complex app with lots of third-party integrations? Need good code splitting, use of static assets, and CommonJs dependencies? Use webpack.

(Video) Vite in 100 Seconds

Personally, I will continue to prefer webpack for my projects. One might argue that Parcel in many cases offers built-in configurations that might provide ease of development, but it’s difficult to overlook the extensive support and customisability that webpack provides.

At the end of the day, it’s a personal call that every developer needs to make based on their requirements. It’s sort of like the difference between driving a car with an automatic transmission versus a stick shift. Sometimes you need the additional control and sometimes you don’t.


Why Rollup is better than Webpack? ›

webpack and Rollup both require a config file specifying entry, output, loaders, plugins, transformations, etc. However, there's a slight difference: Rollup has node polyfills for import/export, but webpack doesn't. Rollup has support for relative paths in config, but webpack doesn't — which is why you use path.

Which is better Rollup or Webpack? ›

There is a slight difference between rollup and webpack config file. Rollup has node polyfills for import/export, whereas webpack doesn't. Rollup has support for relative paths, whereas webpack does not, so we either use path.

Is Parcel better than Webpack? ›

When you bundle your application initially, usually Parcel takes a considerable amount of time compared to WebPack. WebPack is faster. However, in subsequent builds (when you are watching and building), Parcel is much faster.

What is the best bundler? ›

This article will discuss five-module bundlers you can choose to integrate with your JavaScript projects.
  1. Webpack. Source: Webpack. ...
  2. Browserify. Source: Browserify. ...
  3. FuseBox. Source: FuseBox. ...
  4. Rollup. Source: Rollup. ...
  5. Parcel. Source: Parcel.

Is Rollup faster than webpack? ›

Rollup provides much simpler configuration over webpack 4 and has a host of pre-configured plugins that are a breeze to incorporate into your project. Rollup's also the fastest of the build tools period.

What is the most popular module bundler? ›

Webpack. With over 18 million weekly downloads and 60k GitHub stars, Webpack is currently the most popular JavaScript module bundler.

Is webpack still the best? ›

Loved by many, hated by some, known to all. And still the most popular bundler in 2021. With more than 15 million weekly downloads (at the time of writing this post), there's no doubt that Webpack is still the bundler par excellence in 2021.

Is Rollup deprecated? ›

This package has been deprecated.

What is faster than webpack? ›

Esbuild also takes a traditional bundling approach, but is simply lightning fast. Written in go instead of JavaScript and making healthy use of parallelization, Esbuild is estimated to be 50–100x the speed of other bundlers including Parcel and Webpack.

Are parcel bundlers deprecated? ›

This package has been deprecated.

What are the disadvantages of Webpack? ›

Unfortunately, Webpack is very susceptible to bundle size because each change takes all our dependencies and all the source code and converts it into one enormous JavaScript file, which is then served to the server. As a result, creating such a bundle may take up to several minutes in extreme cases!

Why should I use Rollup? ›

Here are some reasons why you should consider using Rollup in your projects. It offers tree-shaking which removes unused codes for easier project development. Eases application development, since it is easier to work with small manageable files. Rollup is pretty fast and lightweight.

What is the best way to ship multiple packages? ›

If you're only shipping a couple of boxes, USPS is probably the cheapest way. For large or heavy boxes or shipments of more than three boxes, consider the consolidated freight shipping method as the cheapest way to ship boxes when multiple less-than-truckload (LTL, or less-than-load) shipments are combined into one.

Which bundler is best for nodejs? ›

One of the most popular and widely used static Node. js module bundlers is webpack. It follows a basic workflow for module bundling—the dependency graph method.

Is parcel GOOD FOR React? ›

Parcel works great for building single or multi-page React applications. It includes a first-class development experience with Fast Refresh, and supports JSX, TypeScript, Flow, and many styling methodologies out of the box.

Why is Rollup better for libraries? ›

What makes Rollup special is its ability to keep files small. It achieves this in two ways: first due to the fact that Rollup is based on ES modules (more efficient than CommonJS modules); and second because it removes unused code from the produced bundle.

Is Webpack obsolete? ›

The Ecosystem now

The newer bundlers have simpler configuration, allowing people to add/create plugins and configure the setup more easily, and some utilize ESM to make ultra fast reload speeds and smaller bundles. Because of this, Webpack is not the best tool to use anymore.

Why is Webpack so slow? ›

However, due to the additional packaging process, the building speed is getting slower as the project grows. As a result, each startup takes dozens of seconds (or minutes), followed by a round of build optimization.

What is parcel bundler used for? ›

Parcel. js is an open-source bundler. It supports many popular languages like Typescript and SASS, and can also handle file types like images and fonts. Parcel comes with a few extra tools built-in: a development server, diagnostics, minification, and even image compression.

What is the most popular package repository for JavaScript? ›

twbs / bootstrap. The most popular HTML, CSS, and JavaScript framework for developing responsive, mobile first projects on the web.

What bundler does nextjs use? ›

Next. js 13 is the newest version, released by Vercel at the Next. js conference in October 2022. It brings a slew of new features, including a bundler called Turbopack and support for several React-incubated optimizations like React Server Components and streaming rendering.

When should you not use webpack? ›

If your application is fairly small, and you don't have many static assets and you only need to build one Javascript file to serve to the client, then Webpack might be more overhead than you need.

Can webpack replace babel? ›

You can replace the compiler and continue using webpack, or you can use SWC's own bundler called spack, which can completely replace webpack, along with Babel.

Does Next js replace webpack? ›

Vercel is replacing Webpack in Next. js — which has been downloaded more than 3 billion times — with a new Rust-based bundler for JavaScript and TypeScript code in the latest release of Next.

Is Rollup the same as webpack? ›

The webpack config file differs slightly from the rollup config file. Webpack lacks node polyfills for import/export, while Rollup does. Since Webpack does not accept relative paths but Rollup does, we must use either path. resolve or path.

Is Rollup a bundler? ›

Rollup is a module bundler for JavaScript which compiles small pieces of code into something larger and more complex, such as a library or application. It uses the new standardized format for code modules included in the ES6 revision of JavaScript, instead of previous idiosyncratic solutions such as CommonJS and AMD.

Does Rollup support code splitting? ›

For code splitting, there are cases where Rollup splits code into chunks automatically, like dynamic loading or multiple entry points, and there is a way to explicitly tell Rollup which modules to split into separate chunks via the output.

What can I use instead of Webpack? ›

There are some alternatives to Webpack that provide the same functionality as webpack. These alternatives are gulp, babel, parcel, browserify, grunt, npm, and requireJS.

Should I use Babel or Webpack? ›

"Modern Javascript works with all browsers", "Open source" and "Integration with lots of tools" are the key factors why developers consider Babel; whereas "Most powerful bundler", "Built-in dev server with livereload" and "Can handle all types of assets" are the primary reasons why Webpack is favored.

Why is Webpack popular? ›

webpack generates static assets that represent modules with dependencies. There are several popular JavaScript module bundlers including Browserify, rollup, and jspm but webpack remains a favorite because it treats web assets as modules with dependencies.

Why do we use Rollup? ›

ROLLUP enables a SELECT statement to calculate multiple levels of subtotals across a specified group of dimensions. It also calculates a grand total. ROLLUP is a simple extension to the GROUP BY clause, so its syntax is extremely easy to use. The ROLLUP extension is highly efficient, adding minimal overhead to a query.

Why are ZK-rollups better than optimistic? ›

One of the main benefits of zk-rollups is their improved security and privacy, thanks to the use of zero-knowledge proofs to verify transactions. This means that transactions can be verified without revealing any information about the transaction itself, allowing for greater privacy and security.

Is Webpack still the best? ›

Loved by many, hated by some, known to all. And still the most popular bundler in 2021. With more than 15 million weekly downloads (at the time of writing this post), there's no doubt that Webpack is still the bundler par excellence in 2021.

Does Webpack use Rollup? ›

Publishing ES Modules

To make sure your ES modules are immediately usable by tools that work with CommonJS such as Node.js and webpack, you can use Rollup to compile to UMD or CommonJS format, and then point to that compiled version with the main property in your package.json file.

What is the best library management system? ›

Best Library Management Systems include:

Follett Destiny Library Manager, Polaris ILS, Book Systems, Springshare, Sierra ILS, EBSCO Stacks, Apollo ILS (Integrated Library System), EBSCONET Subscription Management, and Ex Libris Alma.

What is library best practice? ›

The Best Practices document for libraries provides a framework to evaluate the library's strengths as well as weaknesses. It also serves as the basis of strategic planning. This document has multiple sections with some repeating. Each section should adhere to certain standards.

How can I increase my library traffic? ›

  1. Offer experiences that can't be replicated online. ...
  2. Create a unique sensory experience. ...
  3. Engage ambassadors and influencers. ...
  4. Promote the library as “the new office” ...
  5. Embrace your biggest asset: your team. ...
  6. Amplify digital resources in the physical space.
Sep 6, 2021

Is rollup the same as webpack? ›

The webpack config file differs slightly from the rollup config file. Webpack lacks node polyfills for import/export, while Rollup does. Since Webpack does not accept relative paths but Rollup does, we must use either path. resolve or path.

What can I use instead of rollup in SQL? ›

SQL CUBE Example

Similar to ROLLUP , CUBE is an extension of the GROUP BY clause. It allows you to generate subtotals for all combinations of the grouping columns specified in the GROUP BY clause.

What are the two types of rollups? ›

There are two types of rollups with different security models:
  • Optimistic rollups: assumes transactions are valid by default and only runs computation, via a fraud proof , in the event of a challenge. ...
  • Zero-knowledge rollups: runs computation off-chain and submits a validity proof to the chain.

What is the downside of ZK rollups? ›

Unlike Optimistic rollups, which use a fully EVM-compatible virtual machine, ZK-rollups use their own virtual machine. This produces the downside of needing high computing power to generate zero-knowledge proof. For this reason, transaction data needs to be further optimized to achieve maximum throughput.

Does polkadot use rollups? ›

Polkadot has the sharding ish architecture but it doesn't have Rollups yet. Currenntly, a lot of Ethereum projects are interested in migrating from Ethreum to Polkadot. And some of the great Ethereum projects have already started using Rollups.

What are the limitations of ZK rollups? ›

ZK-Rollups present some limitations that will need to be overcome to achieve mainstream adoption: Complex validity proofing: Computing a zero-knowledge validity proof is difficult and time-consuming. Therefore, to get maximum throughput, ZK-Rollups require data optimization.


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