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HTTP Security Headers Every Site Needs

Security headers protect your users and your search reputation. Here are the ones that matter and what they do.

Why security headers matter for SEO

Google has confirmed HTTPS as a ranking signal. But HTTPS alone is not enough — security headers tell browsers how to handle your content safely. A site with good headers signals trustworthiness.

The essential headers

Strict-Transport-Security (HSTS)

Tells browsers to always use HTTPS, even if someone types the HTTP URL. Without it, the first request to your site is unencrypted.

Content-Security-Policy (CSP)

Controls what resources your page can load. Prevents cross-site scripting (XSS) by blocking unauthorized scripts.

X-Content-Type-Options

Prevents browsers from guessing a file's content type. Without it, a malicious file disguised as an image could be executed as JavaScript.

X-Frame-Options

Prevents your page from being embedded in an iframe on another site (clickjacking).

Referrer-Policy

Controls how much URL information is sent when a user clicks a link to leave your site. strict-origin-when-cross-origin is the recommended default.

How to check

ColorGears Web Insights analyzes all of these headers in one pass — enter any URL and see exactly which headers are present, which are missing, and what to fix.

Related: Core Web Vitals: What Engineers Need to Know covers the performance side of the page-experience signals.

A practical implementation order

If you are starting from zero headers, add them in this order:

  1. HSTS first — it is a single header and the highest-impact change. Start with a short max-age (300 seconds) and increase once you confirm nothing breaks.
  2. X-Content-Type-Options — a single line, no configuration, no risk of breaking anything.
  3. Referrer-Policy — one line, and the recommended value (strict-origin-when-cross-origin) is the browser default anyway.
  4. X-Frame-Options — one line, unless you intentionally embed your site in iframes elsewhere.
  5. CSP — the hardest one. Start with Content-Security-Policy-Report-Only to see what would break, then tighten.

Do not try to add all headers at once. Each one has its own failure mode, and debugging five at once is five times harder than debugging one.