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Peter Thaleikis 🍪
Peter Thaleikis 🍪

Posted on • Originally published at on

How to improve the security of your Netlify site?

Recently I've rebuilt my blog (this website) using Eleventy and Netlify. Being an engineer, I like to enhance and improve my websites. Sometimes I submit my websites to services checking them to identify new areas of improvement. These services are for example broken link crawlers to find links which aren't working anymore or, a service to check the HTTP headers for potential security enhancements/issues.

The initial security assessment of my Netlify site

As many times before, I entered one of my websites for the check of the security-relevant HTTP headers on The result came back quickly and showed there is a potential to improve the headers. Only "Grade D" according to Scott Helme' site:

Securityheaders Result of my website before any modification

Easy to improve with Netlify' _headers file

The outstanding Netlify developer experience makes it very easy to tweak the headers. Netlify allows you to set additional headers in a file called _headers. This file should live in your "Publish directory". This is often called public/, dist or _site. If you are unsure you can check it in the Netlify admin panel of your site under "Build & Deploy".

The headers file allows you to define headers for different URLs (for example /contact) or URL segments (for example /* for all URLs) of your page. In my case it's very simple as I want to apply the headers to all pages (URLs):

 X-Frame-Options: DENY
 X-XSS-Protection: 1; mode=block
 Referrer-Policy: no-referrer
 X-Content-Type-Options: nosniff

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_headers-file example used on

With these headers I get a significantly improved result and a "Grade A":

Securityheaders Result of my website after tweaking _headers

Adding the header file to your git, pushing it up and deploying shouldn't take more than five minutes and improves the security of your website significantly. I would think these are well invested minutes 🙏️

Top comments (2)

bayuangora profile image
Bayu Angora

Why you choose _headers file rather than default netlify.toml file?

spekulatius1984 profile image
Peter Thaleikis 🍪

It shouldn't make a different afaik. It's a preference question I would think