Disable ETags

Category: Blog • Posted by Jeff Starr • Updated:

This tutorial explains how to disable ETags completely. In many cases, sending ETag headers negatively impacts performance, as explained by the wizards at Google and Yahoo. This tutorial explains how to disable ETags via .htaccess for your Apache-powered website. Two copy/paste steps and done. Estimated time required: 5 minutes.

Copy & Paste

Quick fix? Grab the code:

# Disable ETags
<IfModule mod_headers.c>
	Header unset ETag
</IfModule>
FileETag None

That is the basic code required to completely disable ETags. Continue reading for a more elaborate technique and tutorial.

Step 1: Unset ETag and set Cache-Control headers

This step ensures that all ETag headers are unset (first line). Then it sets some basic Cache-Control headers to help optimize performance. So first step: add the following directives to your site's root .htaccess file:

<IfModule mod_headers.c>
	
	Header unset ETag
	
	<filesMatch "\.(ico|jpe?g|png|gif|swf)$">
		Header set Cache-Control "max-age=2592000, public"
	</filesMatch>
	<filesMatch "\.(css)$">
		Header set Cache-Control "max-age=604800, public"
	</filesMatch>
	<filesMatch "\.(js)$">
		Header set Cache-Control "max-age=216000, private"
	</filesMatch>
	<filesMatch "\.(x?html?|php)$">
		Header set Cache-Control "max-age=420, private, must-revalidate"
	</filesMatch>
</IfModule>

The Cache-Control rules we are using here are pretty basic, so feel free to beef ’em up with something more robust. The main thing here is to unset the ETag header (first line), and then also make sure that you're sending Cache-Control headers with each response. The far-future expires headers eliminate any need for ETags.

Step 2: Disable ETags

Now that we're sending far-future expires headers (previous step), we can disable all ETags that otherwise would have been sent by the server. So last step: add this line after the previous set of rules:

FileETag None

That's all there is to it. You can verify that ETags are not being sent using an online tool or browser extension that examines request headers. Performance boost, here we come!