React Native API Parity with JSI & Fabric

The bridge is broken. But from its ashes, something extraordinary is emerging.

Picture this: You're in a critical architecture review meeting. Your mobile app's performance is stuttering under load, the development team is struggling with inconsistent API behaviors across platforms, and stakeholders are questioning whether React Native was the right choice. Sound familiar? If you've been building mobile applications at scale, you've likely faced this moment of reckoning.

The good news? Since 2018, the React Native team has been redesigning the core internals of React Native to enable developers to create higher-quality experiences. As of 2024, this version of React Native has been proven at scale and powers production apps by Meta.

Today, we're standing at the threshold of a fundamental shift in how we approach cross-platform development. The React Native New Architecture—powered by Fabric, JSI, and TurboModules—isn't just an incremental update. It's a complete reimagining of what's possible when we bridge the gap between web and native development.

The Pain We've All Felt

Before we dive into the solution, let's acknowledge the elephant in the room. Traditional React Native architecture has been hobbled by the infamous "bridge"—a serialization bottleneck that has frustrated developers for years. Every interaction between JavaScript and native code required costly JSON serialization, creating performance headaches that kept us awake at night.

As technical leaders, we've all made those difficult trade-offs: accepting slower performance for development velocity, dealing with platform-specific workarounds, or explaining to stakeholders why certain web APIs couldn't be seamlessly implemented in mobile apps.

Enter the New Architecture: A Technical Renaissance

The React Native New Architecture represents a paradigm shift that addresses these fundamental challenges. At its core, it introduces JSI (JavaScript Interface) for seamless JavaScript-to-native communication, TurboModules for optimized native module management, Fabric for a faster and more flexible rendering system, and Yoga for efficient layout calculations.

JSI: The Bridge Killer

The JavaScript Interface (JSI) is perhaps the most revolutionary component of this new architecture. This architecture introduces JSI (JavaScript Interface) to replace the old "bridge" mechanism, allowing direct communication between JavaScript and native code without unnecessary overhead.

JSI enables:

Direct function calls between JavaScript and native code
Synchronous native method execution without serialization delays
Memory sharing between JavaScript and native layers
True web API parity through native implementations

This isn't just about performance—it's about unlocking new possibilities for API consistency across platforms.

Fabric: Reimagining the Rendering Pipeline

Fabric is a complete overhaul of React Native's rendering system. Unlike the legacy architecture that processed UI operations asynchronously, Fabric provides:

Synchronous and asynchronous rendering capabilities
Improved layout calculations through the Yoga engine
Better error handling and debugging experiences
Enhanced accessibility features

Fabric uses JSI to communicate with Hermes and native code, without using the bridge. Fabric is a new rendering system for React Native, seeking to improve the interoperability of the framework with host platforms.

TurboModules: The Performance Multiplier

TurboModules are the next generation of native modules in React Native. Unlike traditional native modules, TurboModules offer:

Lazy loading of native modules
Type safety through code generation
Reduced startup times by loading only required modules
Better memory management and resource utilization

Implementing Web-API-Parity: The Strategic Approach

Now, let's get to the heart of the matter: implementing web-API-parity. This isn't just about making web APIs work on mobile—it's about creating a unified development experience that doesn't compromise on performance or native capabilities.

1. Leveraging JSI for Direct API Implementation

With JSI, we can implement web APIs directly in native code while maintaining the same JavaScript interface. This means:

// Instead of bridged async calls
const result = await NativeModule.expensiveOperation(data);

// We can now have synchronous, direct calls
const result = global.nativeAPI.expensiveOperation(data);

This approach eliminates the serialization overhead and provides true web API parity without performance compromises.

2. Fabric-Powered UI Consistency

Fabric enables us to implement web-like rendering behaviors while maintaining native performance. Key strategies include:

Synchronous layout calculations that mirror web rendering
Consistent event handling across platforms
Predictable component lifecycle management
Web-compatible styling behaviors

3. TurboModule-Based API Implementations

TurboModules allow us to create lightweight, efficient implementations of web APIs:

// Define a TurboModule spec for web API parity
export interface WebAPISpec extends TurboModule {
  readonly getConstants: () => {};
  fetch(url: string, options: Object): Promise<Response>;
  localStorage: {
    getItem(key: string): string | null;
    setItem(key: string, value: string): void;
    removeItem(key: string): void;
  };
}

Performance Impact: The Numbers That Matter

A compelling reason to use React Native instead of WebView-based tools is to achieve at least 60 frames per second and provide a native look and feel to your apps. The new architecture delivers on this promise by:

Eliminating bridge serialization overhead
Reducing JavaScript-to-native call latency
Improving memory management efficiency
Two key metrics define the React Native app's performance: Time to Interactive (TTI): How quickly your app becomes usable after launch... Frames Per Second (FPS): How smoothly your UI renders and responds.

Real-World Implementation Strategy

For teams looking to implement web-API-parity, here's a pragmatic approach:

Phase 1: Foundation Setup

Migrate to React Native 0.76+ to access the new architecture
Enable Fabric and TurboModules in your project configuration
Audit existing native modules for new architecture compatibility

Phase 2: Core API Implementation

Identify critical web APIs your application depends on
Create TurboModule specifications for each API
Implement native counterparts using JSI for direct communication
Ensure type safety through proper specification definitions

Phase 3: Optimization and Testing

Performance profiling to validate improvements
Cross-platform testing to ensure API consistency
Progressive rollout to validate stability at scale
Monitoring and metrics collection for ongoing optimization

The Challenges We Must Address

While the new architecture offers tremendous benefits, it's not without challenges:

Library Compatibility

Many existing libraries haven't been updated for the new architecture. As technical leaders, we need to:

Evaluate library compatibility before adoption
Contribute to open-source updates where possible
Maintain fallback strategies for critical dependencies

Team Training and Adoption

React Native is evolving into a more powerful, cross-platform framework with its new architecture (Fabric, TurboModules, JSI) and broader ecosystem integration. This evolution requires:

Upskilling development teams on new architecture concepts
Establishing new development and testing workflows
Creating documentation and best practices for your organization

Migration Complexity

Moving from legacy architecture isn't trivial. Consider:

Gradual migration strategies to minimize risk
Comprehensive testing at each migration phase
Stakeholder communication about timelines and benefits

The Future We're Building

The React Native New Architecture isn't just about catching up to web development—it's about leapfrogging it. We're creating a future where:

Developers write once, deploy everywhere without performance compromises
Web APIs work seamlessly across all platforms
Performance is native-grade regardless of the underlying implementation
Development velocity increases through consistent APIs and tooling

React Native remains a top choice for cross-platform app development in 2025, and with the new architecture, it's poised to dominate the next decade of mobile development.

Your Next Steps

As technology leaders, we have a responsibility to evaluate and adopt technologies that will serve our teams and users for years to come. The React Native New Architecture represents one of the most significant advances in mobile development since the introduction of React Native itself.

Start by:

Evaluating your current architecture and identifying pain points
Planning a migration strategy that aligns with your development roadmap
Investing in team education on the new architecture components
Beginning with pilot projects to validate the approach in your environment

The bridge is broken, but from its ashes, we're building something extraordinary. The question isn't whether to adopt the new architecture—it's how quickly you can embrace the future of mobile development.

The revolution is here. Are you ready to lead it?

This article reflects the current state of React Native's New Architecture as of 2024-2025. For the most up-to-date technical specifications and implementation guides, consult the official React Native documentation and the React Native Community discussions.

Implementing Web-API-Parity in React Native with Fabric & JSI: The Architecture Revolution That's Reshaping Mobile Development