---
description: Configure how Next.js will dispose and keep in memory pages created in development.
---

# Configuring onDemandEntries

Next.js exposes some options that give you some control over how the server will dispose or keep in memory built pages in development.

To change the defaults, open `next.config.js` and add the `onDemandEntries` config:

```js
module.exports = {
  onDemandEntries: {
    // period (in ms) where the server will keep pages in the buffer
    maxInactiveAge: 25 * 1000,
    // number of pages that should be kept simultaneously without being disposed
    pagesBufferLength: 2,
  },
}
```

## Related

<div class="card">
  <a href="/docs/api-reference/next.config.js/introduction.md">
    <b>Introduction to next.config.js:</b>
    <small>Learn more about the configuration file used by Next.js.</small>
  </a>
</div>
