How to Reduce React Native App Size: Key Optimization Techniques

As you add new features, libraries, images, fonts, and so on to a React Native app, it grows in size. The larger the app, the more storage it requires, and the longer it may take to download and install. This might be an issue for those with limited space or slower internet access.

App size can also impact the installation process. According to Google Play, app size can impact install and uninstall metrics. It also presents a warning screen with ‘large' size to indicate apps larger than 200 MB if they are installed over mobile data.

Fortunately, there are options available to lower app size without losing key features. In this blog, you will learn how to optimize dependencies, JS, images, assets, and Android and iOS production builds to help reduce your app size while using React Native. A reliable React Native app development company can help you apply these practices early in the development process.

Factors That Increase React Native App Size 

A React Native app can grow as more features, libraries, native modules, and resources are added. This size generally doesn't come from one part of the application. It accumulates with project development.

Here are some of the main factors that can increase app size:

• JavaScript code and dependencies: More application code and third-party packages can increase the JavaScript bundle.
• Heavy libraries: When you only use part of the functionality of a library, it may include a lot of code or native resources.
• Images and media: High-resolution images, videos, audio files, and other bundled resources can add significant size.
• Fonts and icons: Unused fonts and icons can bloat the app.
• Native modules: Add extra code and resources to the app using native Android or iOS libraries.
• Multiple device resources: Android apps can distribute multiple resources or native libraries together in the app package. Android App Bundles can help Google Play to deliver optimized APKs, which can help to improve download efficiency.
• Unused resources: Files, code, etc. that are no longer needed in a project can still be in the project.

There may be additional tools and resources for testing and debugging in development builds. A production build provides better insight into what users could download.

Once you know this, it is easier to identify where the additional size is coming from and how to maximize the space.

How to Reduce React Native App Size

A smaller app doesn't necessarily mean fewer features. The best way is to identify what is causing the app to be large and then optimize that. Here are some practical ways to keep a React Native app lightweight.

Measure App Size Before Optimizing

Check the size of your production build before making any changes. A development build might contain additional tools and files that are not included in the app.

Make sure to check the Android and iOS builds separately. Review the JavaScript code, libraries, images, fonts, and more. Android Studio's APK Analyzer and Xcode can help you determine the space consumption.

Note the current size. Make changes and build again, and compare. This will help you to know which changes are shrinking your React Native app size.

Reduce unused dependencies and JavaScript bundle size

Each library you add can increase the size of your app. Some libraries may also include features your app doesn't need.

First, review project dependencies. Eliminate unused packages; don't pile up a huge library for a modest need. If possible, select a smaller alternative.

Also, eliminate unused JavaScript code and load only the code your app requires. Use a library that allows imports of only functions you are using.

Regularly review your dependencies to keep your app small as the project grows. It also helps manage the React Native bundle size.

Optimize Images, Fonts, and Other Assets

Your app may be very large if you include images and other files. If a large image is not really essential, it is much better to use smaller versions that still provide visual quality.

Optimize images and apply the proper dimensions for each screen. When appropriate, formats like WebP can also help to make an image smaller.

Then examine your fonts and icons. Remove unused fonts, font weights, and icons from the project. Repeat the same for old images and other resources that you no longer need.

Big videos and audio files can also be a problem. If the users don't need these files right away, load them on demand instead of putting everything in the initial app download.

These quick steps are crucial to React Native app optimization. 

Check Hermes and JavaScript Loading 

Modern react native projects use the JavaScript engine Hermes. It tunes how JavaScript executes in the app and is now the default for new React Native projects.

Don't change the configuration without checking; ensure your project is using the correct Hermes setup for your React Native version. Then compare your color before and after any changes.

You can also defer loading large features until they're needed. A feature that is rarely used doesn't necessarily require loading at app launch.

The secret is to keep your JavaScript code efficient, but not overly complicated.

Optimize Android Production Builds

Android offers several easy methods to decrease the size of the ultimate app.

• Use R8: R8 can remove code your app doesn't use from the production build.
• Unused resources: Unused images and other resources used by Android can be removed from the release build too.
• Use Android App Bundle: If you publish it via Google Play, then use AAB. Google Play will then be able to send only the resources for a user's specific device to that user, instead of sending them to all users.
• Update native libraries: Review native libraries added by third-party library packages, and delete the libraries that are no longer needed for the app.

Once these changes are made, be sure to test the production build to ensure that all features remain functional.

Optimize iOS Production Builds.

It's the same with iOS too. First of all, remove unnecessary dependencies, images, fonts, etc.

Then go into the production archive size and see it in Xcode. In addition, Apple's App Thinning also provides the necessary resources to the user's device without requiring much data to be downloaded.

If you have some content that you want to display but isn't essential for everyone to have right away, you may want to load it upon demand instead of putting it in the initial application installation.

Before releasing, always test it out on supported devices for the final production build.

Check App Size After Major Updates

Optimizing an app size is not a single activity; it is a continuous process. You can add another feature or library, and you will have to add more to your app again.

After adding critical features/dependencies, review app size. Compare to previous releases and explore any unanticipated rise.

Regular checks can detect size issues early and ensure that your app remains light as it grows.

Things to Avoid Doing When Shrinking an App Size

App size reduction takes planning. Avoid altering without measurement and testing to improve the app, as this may create new issues.

• Optimizing without measuring first: Always check your production build size before making changes. This will allow you to see what really makes your app larger.
• Removing dependency without checking usage: Ensure that a package does not rely on another feature before removing it.
• Testing only development builds: Development builds can include extra tools and resources. Please review the release build prior to any final decision.
• Forget about images and other assets: Large images, fonts, videos, and more can make an app big.
• Doing it all with Hermes: Hermes can help with the performance of JavaScript, but not automatically with large assets, dependencies, or native libraries.
• Applying aggressive Android shrinking: Code and resource shrinking can affect app functionality if you don't test properly. Check some of the key features once these options are turned on.
• Don't remove CPUs to save space: Avoid removing CPU architectures simply to save space. Ensure that the app supports all the devices you require.
• Using percentages: Each application has its own set of percentage claims. Don't assume a percentage drop; measure your own app.

When to Hire React Native Developers?

When an app gets tough to manage, professional React Native support can help. This is typically true for large codebases with many third-party dependencies. For complex Android and iOS builds, expertise is also required.

If your app is getting bigger with each update, you might need professional assistance. This is also true if performance or build problems persist after frequent optimization.

A proficient developer can analyze the application architecture, dependencies, assets, and build configuration. They can identify unnecessary size and suggest sensible changes.

If you want to optimize an existing app without affecting its features, Hire React Native Developers with experience in production apps. An experienced App Development company can help improve the app while keeping it stable and reliable.

Conclusion

Application size control is a continuous process. First, measure the production build and find out which area is most occupied. Next, check your dependencies, JavaScript code, images, fonts, and more.

Android and iOS builds must be updated as well. Test each optimization to ensure it doesn't affect important features. Keep monitoring app size while adding new features and dependencies.

If you wish to lighten your app size without compromising the user experience, an expert USA Mobile App Development Company can help audit your application and implement the correct optimization method. React Native performance optimization can also help keep your app running smoothly.

Need help optimizing your React Native app? Contact iQlance today.

FAQs

Why is my React Native app so big?

You could have unnecessary dependencies, JavaScript files, images, fonts, etc. within your app. The final app size can also be increased by using a large native library. Review your production build to find out where all your space is going.

How to make the react native java script bundle smaller?

Remove unused packages and JavaScript code. When possible, avoid large libraries: Import only the parts of a library that your app needs.

Is Hermes good for reducing the size of the React Native app?

Hermes can also optimize the performance of JavaScript and can also help reduce the size of your app. It will not remove large images, dependencies, or native libraries, however. Review the entire app before making changes.

What is the best way to optimize image size in a React Native app?

Optimize images and use appropriate sizes per screen. WebP can also reduce image file sizes if applicable to your app. Clean up images that are no longer required.

Can Android App Bundle decrease the size of the App download?

Yes. Google Play can only provide resources for the user's device. This can reduce the amount of data users download.

How to make the React Native App smaller on iOS?

Clean up unused files, dependencies, images, fonts, etc. Optimize large resources in the production build in Xcode. Test the final build prior to release.