---
title: "Cache-Control header check — Lemwatch Help"
description: "Grades your Cache-Control headers on static assets, HTML, and API responses — bad caching is a leading hidden cause of slow LCP."
canonical: "https://lemwatch.com/help/cache-control-header-check"
source: "https://lemwatch.com"
---

# Cache-Control header check

> Grades your Cache-Control headers on static assets, HTML, and API responses — bad caching is a leading hidden cause of slow LCP.

## Quick answer

 Lemwatch samples 20 assets per page load and grades Cache-Control against Google's recommendations.

## What it checks

- Static assets: max-age ≥ 1 year + immutable

- HTML: no-cache or short max-age

- API JSON: private + short max-age

- Missing Cache-Control (worst case) flagged

## Where to find it in Lemwatch

 **Site details → Performance → Caching.**

## How to fix

- Fingerprint asset filenames ( app.abc123.js ).

- Serve fingerprinted assets with Cache-Control: public, max-age=31536000, immutable .

- HTML gets Cache-Control: no-cache so users see deploys immediately.

- Re-run.

## FAQ

### Is immutable safe?

 Yes — as long as filenames change on every deploy.

### What about ETag?

 Still useful, but Cache-Control is the primary signal.

## Related

- Performance budgets

- Gzip/Brotli compression check

- Core Web Vitals


## Related

- [Help centre](https://lemwatch.com/help)
- [Setting Performance Budgets](https://lemwatch.com/help/performance-budgets)
- [Gzip / Brotli compression check](https://lemwatch.com/help/gzip-brotli-compression-check)
- [Core Web Vitals Explained](https://lemwatch.com/help/core-web-vitals)
- [Canonical tag check](https://lemwatch.com/help/canonical-tag-check)
- [Robots.txt check](https://lemwatch.com/help/robots-txt-check)
- [Lemwatch pricing](https://lemwatch.com/pricing)
- [How do I cancel my subscription?](https://lemwatch.com/help/cancel-subscription)