next.js/docs/01-app/03-api-reference/05-config/01-next-config-js/reactStrictMode.mdx

---
title: reactStrictMode
description: The complete Next.js runtime is now Strict Mode-compliant, learn how to opt-in
---

{/* The content of this doc is shared between the app and pages router. You can use the `<PagesOnly>Content</PagesOnly>` component to add content that is specific to the Pages Router. Any shared content should not be wrapped in a component. */}

> **Good to know**: Since Next.js 13.5.1, Strict Mode is `true` by default with `app` router, so the above configuration is only necessary for `pages`. You can still disable Strict Mode by setting `reactStrictMode: false`.

> **Suggested**: We strongly suggest you enable Strict Mode in your Next.js application to better prepare your application for the future of React.

React's [Strict Mode](https://react.dev/reference/react/StrictMode) is a development mode only feature for highlighting potential problems in an application. It helps to identify unsafe lifecycles, legacy API usage, and a number of other features.

The Next.js runtime is Strict Mode-compliant. To opt-in to Strict Mode, configure the following option in your `next.config.js`:

```js filename="next.config.js"
module.exports = {
  reactStrictMode: true,
}
```

If you or your team are not ready to use Strict Mode in your entire application, that's OK! You can incrementally migrate on a page-by-page basis using `<React.StrictMode>`.