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Hermes

Hermes is React Native's optimized JavaScript engine that improves app performance, reduces memory usage, and decreases app size. Discover how to enable and configure Hermes, debug applications effectively, and leverage its capabilities to create faster, more efficient React Native applications.

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Why You Don’t Have to Minify JavaScript Code in React Native Apps

React Native skips JavaScript minification in production because Hermes handles dead code elimination at the bytecode level. Here’s how and why it works.

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From Static Hermes to Hermes V1: The Road to Default

Nicola Corti (Meta) explains the evolution of Static Hermes into Hermes V1, the performance boosts it ships, and the (experimental) path to making it the new default engine.

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Hermes V1: What It Is, What It Isn’t, and What’s Next

Łukasz Chludziński, Szymon Chmal, and Matt Hargett unpack Hermes V1, covering what’s new, what’s changing, and what’s ahead for React Native performance.

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How to Optimize Your Android App Startup Time With Hermes

Learn how to achieve better performance and optimize Android app startup time with Hermes.

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Technical Guide, Part 2: Integrating Hermes With React Native

Interested in the Hermes engine? Check the second part of our expert guide to find out how to integrate Hermes with React Native.

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Technical Guide, Part 1: Compiling Hermes for Apple Platforms

Want to use Hermes in your React Native app on iOS? Find out how to compile Hermes for Apple platforms. Check the first part of our expert technical guide.

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React Native 0.64 With Hermes for iOS

Discover how Hermes boosts React Native performance on iOS and macOS, with insights into AOT, bytecode precompilation, and the future of Hermes support.

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Hermes Performance on iOS

Wondering how the Hermes engine performs on iOS? We tested it on a React Native mobile app. Check the results and see how it compares to JSC.

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Bringing Hermes to iOS in React Native 0.64

Hermes is now available for iOS as well. Find out more about this JS engine - check the first part of our series on bringing Hermes to iOS.

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Want to achieve better performance with Hermes?

We guide teams in optimizing React Native with the Hermes engine.

2×Estimated AI-assisted delivery speedupJetBrains
25Working days from kickoff to mergeJetBrains
1Plugin across three frameworksJetBrains
10min from code change to mini-app releaseTeamworks
multi-dailystaging deployments instead of weekly releasesTeamworks
7mini-apps supported in one modular mobile platformTeamworks
2CI/CD lanes for mini-app and host-app distributionTeamworks
2xgrowth in mobile user base during the migration periodAutoZone
4.2 -> 4.7app rating increase after migrating to React NativeAutoZone
0missed releases during the transition to React NativeAutoZone
33%fewer re-renders across most featuresQuestrade
18%faster time-to-interactiveQuestrade
-28%CPU usage in critical trading flowsQuestrade
78%bundle size reduction (from 50 MB to 11 MB)Dream11
30%faster component mount time after render optimizationDream11
60%faster initial load time enabled by switching to HermesDream11
5xfaster message sending timeExpensify
4.5xfaster search screen loading timeExpensify
#1SEO rank, recovering from 3-9AutoZone
260kBless in blocking JS payloadAutoZone
2–5xfaster feedback loopAutoZone
2.8xincrease in knowledge over 8 weeks (25% → 71% assessment scores)Hello Fresh
15developers trained across web and native backgroundsHello Fresh
86%of devs self-rated their knowledge as 3/5 or higher after training (up from 0%)Hello Fresh
130%increase in users post-upgrade7cups
63%adoption rate; majority of attendees registered in the appReact Universe App
67%of attendees connected through QR badge sharingReact Universe App
45%created personalized badges to showcase identity and goalsReact Universe App
49%of attendees onboarded before day one, arriving ready to networkReact Universe App

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