Website Security Header Checklist

Security headers provide browser-level protections against common attacks. Content-Security-Policy (CSP) helps prevent cross-site scripting by controlling which resources the browser can load. Strict-Transport-Security (HSTS) forces browsers to use HTTPS. X-Frame-Options prevents clickjacking. X-Content-Type-Options prevents MIME type sniffing.

These headers can disappear silently after platform changes. A migration, plugin update, or hosting configuration change can remove headers without the site owner noticing. The site continues to function, but visitors lose browser-level protections.

Regular security header checks catch these issues. Including header verification in your health check workflow ensures headers remain in place and visitors stay protected.

Content-Security-Policy (CSP): Is a CSP header present? Does it restrict resource loading to trusted sources? A CSP that allows all inline scripts provides minimal protection. Review the policy to ensure it provides meaningful protection.

Strict-Transport-Security (HSTS): Is HSTS present? Does it include the includeSubDomains directive? HSTS tells browsers to always use HTTPS for your site, preventing protocol downgrade attacks.

X-Frame-Options: Is this header present? Is it set to DENY or SAMEORIGIN? This prevents your site from being embedded in frames on other sites, which protects against clickjacking attacks.

X-Content-Type-Options: Is this header present and set to nosniff? This prevents browsers from MIME type sniffing, which can lead to security vulnerabilities.

Referrer-Policy: Is a Referrer-Policy header present? This controls how much referrer information is sent with requests. A restrictive policy like strict-origin-when-cross-origin is recommended.

Permissions-Policy: Is a Permissions-Policy header present? This controls which browser features (camera, microphone, geolocation) your site can access. Configure this to restrict unnecessary features.

You can check security headers manually by viewing the HTTP response headers in your browser's developer tools. Open developer tools, go to the Network tab, load your site, and examine the response headers for the document request.

Online tools like Mozilla Observatory and SecurityHeaders.com scan your site and evaluate security headers. They provide a grade-based assessment and specific recommendations for improvement. These are useful for one-time checks but do not provide ongoing monitoring.

For ongoing monitoring, include security header checks in your regular health check workflow. MonitorMojo includes security header presence as part of every website health check. Each check reviews whether key headers are present alongside reachability, SSL, response time, and other signals.

Run header checks after every platform change. Migrations, plugin updates, and hosting changes can silently remove headers. A post-change health check verifies headers are still in place.

If a security header is missing, investigate what changed. Was there a recent platform migration, plugin update, or hosting configuration change? The timing of the missing header relative to a change gives a strong signal about the cause.

For WordPress sites, security headers are often configured through plugins or .htaccess rules. A plugin update or conflict can remove these configurations. Check whether a security plugin is active and whether its configuration is intact.

For other platforms, security headers may be configured at the server level (Nginx, Apache) or through a CDN. Check the server configuration and CDN settings to identify where headers should be configured.

Coordinate with the developer or hosting provider to restore the correct header configuration. After restoration, run a health check to verify the headers are present and configured correctly.

Document the issue and resolution. If headers disappeared after a specific type of change, note this for future reference. This helps identify patterns if similar issues recur.

Not checking headers after platform changes is a common mistake. Changes can silently remove headers. Post-change verification catches these issues.

Assuming headers are configured correctly without verification is another mistake. A CSP header that is too permissive provides minimal protection. Check both presence and configuration quality.

Relying on a one-time check instead of ongoing monitoring means you miss headers that disappear after changes. Security headers need to be checked regularly.

Ignoring security headers because they seem too technical is a fourth mistake. While the configuration details are technical, checking whether headers are present is straightforward. If headers are missing, coordinate with a developer to restore them.

MonitorMojo includes security header presence as part of every website health check. Each check reviews whether key security headers are present alongside reachability, SSL, response time, redirect behavior, and domain risk notes.

For agencies, including security header checks in every health check means you can verify that headers remain in place after platform migrations, plugin updates, or hosting changes.

The results depend on hosting, DNS, infrastructure, configuration, traffic, and response process. MonitorMojo helps you see what headers are being served from outside the hosting environment.

Website Security Header Checklist is best understood as a repeatable website health workflow, not a promise that every outage or configuration issue will be avoided. Get a complete website security header checklist covering CSP, HSTS, X-Frame-Options, and more. Learn what headers to check, why they matter, and how to verify them.

In practice, this workflow centers on security header presence, browser-level protections, ownership notes, and review follow-up. Each check is planning input: it can show that the site is reachable, that a certificate has a given expiry window, that response time has shifted, or that a header is missing. It cannot prove root cause by itself or replace a human response. The value is in making the review consistent enough that site owners and small teams can spot issues before someone downstream has to ask about them.

This is most useful for site owners and small teams. Agencies verifying security headers across client sites

Beyond that primary audience, the same checks are reusable by anyone with a public-facing URL that matters to revenue, leads, or reputation: a recurring review is cheap insurance compared to hearing about the problem from a client or customer first.

Start by listing the URLs that actually matter instead of just the homepage — for a small team doing a routine check before something breaks in front of a visitor, that usually means the pages tied to revenue, signups, or trust, not every page on the site.

Next, define the check types for each URL: reachability, HTTP status, HTTPS/SSL certificate status and expiry window, response time, redirect behavior, and security header presence. For API, CLI, and AI-agent workflows, document which endpoint or command runs the check and where the result is stored.

Set a cadence that matches the risk — a low-traffic page may only need a monthly look, while a page tied to revenue or signups deserves a check after every deployment and before any campaign or launch.

Record what you find with a consistent format: URL, check type, status, issue, owner, detected date, and next review date. Then say what actually happened in plain language — a check can surface a symptom, but site owners and small teams still need to confirm the cause.

• Choose the URLs that matter most to visitors, clients, revenue, and operations.
• Run uptime, SSL, response time, and security header checks on a consistent schedule.
• Triage failed or risky checks by likely owner: hosting, DNS, SSL, code, platform, or third party.
• Record notes in a repeatable format so future reviews do not start from scratch.
• Send a plain-language summary with the issue, impact, owner, and next review date.
• Run a confirmation check after remediation so there is an external result to reference.

Use this template for recurring reviews: [URL], [Check Type], [Status], [Issue], [Priority], [Owner], [Detected Date], [Resolved Date], [Next Review Date]. Add a one-line summary at the top: what changed, what needs attention, and who owns the next step.

For site owners and small teams, group findings into the four signals that matter most: reachability, SSL status, response time, and security headers. Where nothing needs action, say the check found no issue in that area rather than implying full coverage.

• [URL]: the exact page or endpoint checked.
• [Check Type]: uptime, SSL, response time, headers, API, CLI, or agent workflow.
• [Status]: pass, review, failed, blocked, or needs human investigation.
• [Issue]: the observable symptom, not an unsupported root-cause claim.
• [Owner]: agency, developer, host, DNS provider, client, or third-party vendor.
• [Next Review Date]: when the team should confirm status again.

The most common mistake is monitoring only the homepage while a checkout, signup, or booking flow silently breaks. Another is assuming SSL auto-renewal always works — it can fail quietly, and an external check is the only way to catch that before a browser warning does.

For site owners and small teams specifically, the recurring miss is treating one clean check as proof the whole site is fine, or fixing an issue without ever writing down what happened — which means the next person repeats the same investigation from zero.

• Tracking too many low-value URLs while missing the ones that matter.
• Skipping notes after an issue is resolved.
• Reporting a status without an owner or next step attached.
• Assuming automation can resolve an incident without human review.
• Treating one clean check as proof that every risk is covered.

Consider a small team doing a routine check before something breaks in front of a visitor. A scheduled check flags that the site is slower than its usual baseline and that a security header is missing. Instead of guessing, the team logs the observation with a timestamp, assigns an owner, and re-checks after the fix ships — turning a vague "something feels off" into a specific, closed-loop task.

MonitorMojo runs website health checks that combine reachability, SSL certificate status, response time, and security header presence in one workspace, so this workflow doesn't require stitching together several separate tools.

The API and CLI make the same checks scriptable for site owners and small teams who want them wired into an existing process, while credit-based checks keep it practical to run reviews exactly when they matter — before a client call, after a deploy, or when someone asks whether the site is healthy. Results still depend on hosting, DNS, and how quickly the responsible team acts on what the check finds.