# Back/forward cache

Category: [Performance & Core Web Vitals](https://seo-geo-glossary.com/en/glossary/category/performance-core-web-vitals/) › [Optimization](https://seo-geo-glossary.com/en/glossary/category/performance-core-web-vitals/optimization/) · Also known as: bfcache

The **back/forward cache (bfcache)** is a browser optimization that keeps a complete snapshot of a page in memory when a user navigates away. If the user presses Back or Forward, the browser restores the page instead of loading it again.

## How does it differ from the HTTP cache?
The HTTP cache stores individual responses. The bfcache stores the whole page, including the JavaScript heap, with running code paused. According to web.dev, a bfcache restore is essentially instant. It is a browser feature and not a ranking factor, but web.dev notes that restores can improve Core Web Vitals in field data.

## What blocks the bfcache?
web.dev and MDN name these common blockers:

- an `unload` event listener, so use `pagehide` instead
- open connections such as WebSocket or in-flight fetch requests
- open IndexedDB transactions
- `Cache-Control: no-store` on the page. Chrome allows bfcache for such pages under conditions, for example when cookies do not change. Its documentation describes the final rollout to all users in March and April 2025.

## Example
In Chrome DevTools, open Application, then Back/forward cache, and run the test. It reports either success or the reason the page was not restored. In code, the `persisted` property shows a restore:

```js
window.addEventListener('pageshow', (event) => {
  if (event.persisted) {
    // page was restored from the bfcache
  }
});
```
Pages restored this way do not fire a normal load, which matters for analytics. The `notRestoredReasons` API reports blockers from real visits.

## Related terms

- [Google cache](https://seo-geo-glossary.com/en/glossary/google-cache/index.md)
- [Browser caching](https://seo-geo-glossary.com/en/glossary/browser-caching/index.md)
- [Cache-Control](https://seo-geo-glossary.com/en/glossary/cache-control/index.md)
- [Core Web Vitals](https://seo-geo-glossary.com/en/glossary/core-web-vitals/index.md)
- [Largest Contentful Paint (LCP)](https://seo-geo-glossary.com/en/glossary/largest-contentful-paint/index.md)

## Sources

- [Back/forward cache – web.dev](https://web.dev/articles/bfcache)
- [bfcache – MDN Web Docs Glossary](https://developer.mozilla.org/en-US/docs/Glossary/bfcache)
- [Chrome: bfcache for Cache-Control: no-store pages – Chrome for Developers](https://developer.chrome.com/docs/web-platform/bfcache-ccns)

---

Last updated: October 7, 2026
URL: https://seo-geo-glossary.com/en/glossary/back-forward-cache/