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React Performance Tool
Nominated for React Open Source Awards 2020

Reactime is an open source Chrome developer tool for time travel debugging and performance monitoring in React applications. Reactime enables developers to record snapshots of application state, jump between and inspect state snapshots, and monitor performance metrics such as component render time and render frequency.

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How To UseFeaturesWebsiteRead More

Reactime 17.0 We are pleased to announce the release of Reactime 17.0, which includes several new and improved features. Context API support has now been added. You can now monitor state stored in context if your component is subscribed to context changes. We also improved the tooltip UI on our tree diagram to improve readability. In addition, we have redesigned the website using Tailwind CSS, resulting in a clean, modern design with an intuitive layout. To stay informed about future updates, you can now sign up for email notifications.

Reactime 16.0 presents the codebase with substantial, much-needed clean-up. From the backend and frontend to testing, the Reactime XVI team has: removed vestigial code, added comments to clarify code, implemented 100% testing coverage for the codebase, compartmentalized and modularized files, and implemented typescript.

The primary purpose of this update is to allow easier understanding of Reactime's codebase by individuals or groups wishing to further update Reactime, keeping this great developer tool alive.

With release of Node v18.12.1(LTS) on 11/4/22, the script has been updated to 'npm run dev' || 'npm run build' for backwards compatibility.
For version Node v16.16.0, please use script 'npm run devlegacy' || 'npm run buildlegacy'

Previously, Reactime 14.0 and 15.0 added the exciting features below:

I. React Router Compatibility
Reactime is now compatible with React Router applications! Prior to Reactime 14.0, recording state snapshots as the user navigated across various routes was possible, but time travel debugging was only possible for the current route (i.e. jumping back to a prior state at a different route was not possible). In order to streamline debugging of applications with multiple routes, Reactime 14.0 added functionality that allows the user to time-travel back to different routes, including live updating in the browser to reflect the state of their application at that previously visited route.

II. Classifying State Snapshots by Route
The list of state snapshots in the Reactime dashboard is now classified by route to give the developer visual cues of the snapshot-route relationship and make time travel debugging of various routes easier.

III. Filtering Performance Metrics By Route
The Reactime dashboard includes a stacked bar graph showing render times for each component, with a separate bar stack for each snapshot. With Reactime 14.0, this composite bar graph can now be filtered by route to allow the developer to review detailed performance data by route.

IV. Visualize And Compare Components Within a Snapshot
Users not only have access to multiple snapshots, but can now zone into a specified snapshot more granularly through a new visualization consisting of its individual components. These new graphs are rendered directly in the same Performance tab in Reactime and provide details for each component when the user hovers over, providing a new visual comparison of components across a single chosen state.

After installing Reactime, you can test its functionalities with your React application in development mode.

Please note, the time jumping feature will ONLY work when your application is running in development mode. In production mode, you are able to view your application’s component map but no additional features.


To get started, install the Reactime extension from Chrome Web Store.

NOTE: The React Developer Tools extension is also required for Reactime to run, if you do not already have it installed on your browser.

Manual Installation

Go to Chrome Extensions (make sure Chrome Extension is in Developer Mode) for manual installation in ( and click on Load Unpacked. Use src/extension/build/ to load this extension. Turn on 'Allow access to file URLs' in extension details page if testing locally.

Looking to contribute to Reactime?

Please refer to Developer Install for a detailed guide: Developer Install

After you finish the Develpoer Install, checkout the developer README for more info on the project, and instructions on building from source.

How to Use

After installing the Chrome extension, just open up your project in the browser.

Then open up your Chrome DevTools and navigate to the Reactime panel.


Why is Reactime telling me that no React application is found?

Reactime initially runs using the dev tools global hook from the Chrome API. It takes time for Chrome to load this. Try refreshing your application a couple times until you see Reactime running.

There is a black screen instead of the Reactime extension

Try refreshing the application you want to test and refresh the DevTools by clicking the right mouse button “Reload frame”.

I found a bug in Reactime

Reactime is an open source project, and we’d really appreciate your help with improving user experience. Please read the developer README, and create a pull request (or issue) to propose and collaborate on changes to a repository.

Node version compatiability

With release of Node v18.12.1(LTS) on 11/4/22, the script has been updated to 'npm run dev' | 'npm run build' for backwards compatibility.
For version Node v16.16.0, please use script 'npm run devlegacy' | 'npm run buildlegacy'


🔹 Viewing

You can view your application's file structure and click on a snapshot to view your app's state. State can be visualized in a Component Graph, JSON Tree, or Performance Graph. Snapshots can be diffed with the previous snapshot, which can be viewed in Diff mode.

🔹 Snapshot Series and Action Comparison

You can save a series of state snapshots and use it to analyze changes in component render performance between current and previous series of snapshots. You can also name specific snapshots and compare all snapshots with the same name.

🔹 Components Comparison

When toggled to a specific snapshot, a visualization of the individual components of the snapshow will be displayed. This can be done under the same Performance tab where the snapshots are rendered. You will also find details of each component upon hovering.

🔹 Recording

Whenever state is changed (whenever setState, useState is called), this extension will create a snapshot of the current state tree and record it. Each snapshot will be displayed in Chrome DevTools under the Reactime panel.

🔹 Re-render Optimization

One of the most common issues that affects performance in React is unnecessary render cycles. This problem can be fixed by checking your renders in the Performance tab in Chrome DevTools under the Reactime panel.

🔹 Jumping

Using the actions sidebar, a user can jump to any previous recorded snapshots. Hitting the jump button on any snapshot will allow a user to view state data at any point in the history of the target application.

🔹 Gatsby

Reactime offers full support for Gatsby applications. You would be able to identify unnecessary renders, duration of each rendering, travel-debugging features and visual representation of the tree components.

🔹 Next.js

Reactime offers debugging and performance tools for Next.js apps: time-traveling debugging, preventing unnecessary components re-renders and making your application faster.

🔹 TypeScript Support

Reactime offers support for TypeScript applications using stateful class components and functional components. Further testing and development is required for custom hooks, and Concurrent Mode.

🔹 Documentation

After cloning this repository, developers can simply run npm run docs at the root level and serve the dynamically generated /docs/index.html file on a browser. Doing so will provide a readable, extensible, and interactive GUI view of the structure and interfaces of the codebase.

Additional Features

  • Identifying unnecessary re-renders
  • Single-click to view tooltip details on state visualizations
  • Double-click to collapse child components
  • A reverse filter with autofill to focus on a portion of the component map
  • Ability to pan and zoom on state visualizations
  • A dropdown to support development of projects on multiple tabs
  • A slider to move through snapshots quickly
  • A play button to move through snapshots automatically
  • A lock button, which stops recording each snapshot
  • A persist button to keep snapshots upon refresh (handy when changing code and debugging)
  • Download/upload the current snapshots in memory
  • Declarative titles in the actions sidebar
  • Interative Tutorial Walkthrough
  • Toggle feature allowing temporary pause of state monitoring
  • Updated frontend diagram:

Bug Fixes

  • Search bar now searches for specific nodes successfully
  • Tab titles of chrome browser tabs not running an application in development mode are no longer affected by Reactime
  • Multiple black screens fixed
  • Improved UI and performance
  • No longer inject scripts to non-target applications

Read More



This project is licensed under the MIT License - see the LICENSE file for details.