Fabric renderer + Hermes engine.
JS components map to a native UIView on iOS and android.view.View on Android through the new Fabric architecture, which replaced the asynchronous bridge across 2024 and 2025. Hermes runs the JavaScript: AOT-compiled bytecode with a smaller heap than V8.
Cost: a thin layer of state-translation work per frame, occasionally visible as dropped frames on heavy list scroll. Benefit: a button looks and feels like a real iOS button on iOS and a real Material button on Android, including ripple, haptics, and accessibility behaviors.