Meteor 3.4 is out: Rspack integration, 4x faster builds, 8x smaller bundles, and extended bundler features

Source: Dev.to

What’s New

• Rspack bundler is now part of the core, cutting build times, reducing bundler size, and supporting standard configuration patterns and features from the wider JavaScript ecosystem.
• This release fulfills many long‑requested improvements that have been rolled out throughout the Meteor 3 series.

Recap of Recent Releases

The core team has already migrated the Galaxy Cloud app to Rspack, showcasing real‑world performance gains. This post details those changes and provides metrics you can expect after upgrading to Meteor 3.4.

Community contributions in this release include:

• Stability and performance improvements for Meteor React suspense hooks.
• Integration of the collection-extensions package into core.
• Modern‑build support for Cordova, and more.

Getting Started

Create a New App

# Create a new Meteor app using Meteor 3.4
meteor create my-app --release 3.4

All improvements introduced in Meteor 3.3 and 3.4—including the Rspack integration—are enabled by default for new apps and applied to all skeleton examples. Run meteor create --help to see the available skeletons.

Update an Existing App

# Update your existing Meteor app to version 3.4
meteor update --release 3.4

Enable Meteor Bundler Optimizations

Add the modern flag to your package.json:

{
  "meteor": {
    "modern": true
  }
}

See the Bundler Optimizations requirements for details.

• Docs: ☄️ Meteor Bundler Optimizations

Enable the Rspack Integration

meteor add rspack

Check the Rspack integration requirements for existing apps.

• Docs: ⚡ Rspack Bundler Integration

Highlights

Faster Builds

Meteor 3.4 builds are ~70 % faster (≈ 3.5× speed‑up) thanks to Rspack’s Rust‑based compilation. The Meteor bundler still handles Atmosphere packages, but that part was already optimized in 3.3, giving you the best of both worlds.

These metrics were measured on the Galaxy app after migrating to Rspack. Your app should see similar improvements.

Smaller Bundles

Tree‑shaking is finally available in Meteor 3.4. Combined with Rspack’s chunk splitting, dynamic imports, and minification, bundle sizes shrink dramatically.

• The main client bundle of the Galaxy app dropped ≈ 88 % compared to the 3.3.2 release.
• Smaller bundles mean less code delivered to the browser and faster initial load times.

Gains will vary by application, dependencies, and the specific optimizations you enable, but tree‑shaking alone provides noticeable improvements.

Atmosphere Bundle Reduction

Meteor 3.4 adds an optimization for Atmosphere packages by introducing:

• The ability to mark packages as devOnly, so they’re fully removed from production builds.
• A new Npm.devDepends option in your package.js to define dev‑dependencies, ensuring only the needed node modules for development are included during dev time and excluded from production (meteor build).

After deploying the Galaxy app, the total bundle size stored on the host machine dropped by about 42 %. This improvement applies to all apps, since Meteor core packages now use the new Atmosphere optimization configuration. More gains will come as you update your own Atmosphere packages—or community ones—to properly skip dev‑only packages and dependencies in production builds, leaving your final containers on hosts noticeably smaller.

Modern Setups

Meteor 3.4 introduces Rspack, letting you configure modern setups from the community.

Supported setups include React, React Compiler, Vue, Solid, Svelte, and Angular, all using their latest versions. Legacy setups like CoffeeScript and Blaze remain supported, keeping older projects compatible.

With this update, ESM packages are fully supported. Meteor apps can now use modules that rely on ESM behavior—a clear example is the support for React Router v7, a long‑standing request from the community.

Rspack also opens many new options. All Rspack (or Webpack) features can be configured in Meteor apps, including:

• Workbox for Service Workers and PWA
• Asset imports and optimizations
• Controlling the bundler lifecycle for custom behaviors and improvements

What Else Is New in Meteor 3.4?

Thanks to the commitment of many community contributors, we have expanded this release with new features and optimizations.

• react-meteor-data updated to 4.0.1, bringing improvements to suspense hooks and general optimizations.
  Contributors: @welkinwong, @malua, @evolross, and @StorytellerCZ.

• Integrated collection-extensions into core, part of our goal to bring widely used packages into Meteor core for better support and maintenance.
  Contributor: @harryadel.

• Cordova builds are now considered modern instead of legacy when "modern": true is set in your project’s package.json.
  Contributor: @tmeyer24.

• --raw-logs is now the default in the Meteor CLI for development.
  Suggested by: @paulishca (see the discussion here), with implementation by @Grubba27.

More improvements and fixes were introduced in Meteor 3.4; see the full changelog.

Release Videos

• 📹 Meteor 3.4 and the road ahead – Galaxy Expansion Day 5
• 📹 Modern Build Stack in Meteor 3: Empower Your Meteor Apps with Faster, Feature‑Rich Bundling

Big Thanks to Our Contributors

Reaching the 3.4 milestone would not have been possible without an active and enthusiastic community. We want to highlight how important these contributions have been for this release.

Core contributors:
@nachocodoner, @italojs, @Grubba27, @welkinwong, @harryadel, @vparpoil, @StorytellerCZ, @turoar23, @DipakHalkude, @sanki92, @evolross, @malua, @tmeyer24, @jeetburman, and @copleykj.

Thanks to all community members for testing and providing feedback on Meteor 3.4.

What’s Next for Meteor and Beyond?

For upcoming releases, our priorities are:

• Stability and patches – collect feedback and fix issues. Planned Meteor 3.4.x patches.
• Change streams – unified MongoDB change notifications. Planned for Meteor 3.5.
• Node 24 – align with newer Node LTS releases.
• Native – move toward a modern native solution beyond Cordova.

For more details on upcoming work and priorities, see the Meteor roadmap.

Roadmap

Roadmap

Join the Meteor Renaissance!

Meteor 3.4 wraps up the significant bundler changes we had envisioned. From these changes we will keep tweaking the bundler to expand and improve the experience if needed. Still, we’ll continue updating Meteor to revitalize the framework we all love in other areas as well.

We’re excited about what’s to come and can’t wait for you to join the Meteor renaissance!

For feedback, questions, or support, visit our forums or join our Discord channel.

If you find any issues, please report them to the Meteor issues tracker.

Follow us on Twitter and GitHub.

Stay tuned, and as always, happy coding! ☄️