SecurityHeaders.com made HTTP response header testing popular by turning a site’s configuration into an easy-to-understand grade. It remains a useful focused checker, but another tool may suit you better when you need deeper scan modes, prioritized remediation, an API, scan history, continuous monitoring, broader web checks, or detailed TLS analysis.
We reviewed the current options in July 2026. The best SecurityHeaders.com alternative depends on whether you want a fast one-off check, developer-friendly automation, organization-wide monitoring, or a broader security assessment. The seven tools below cover those use cases without pretending that an automated header scan replaces a complete security review.
SecurityHeaders.com alternatives at a glance
| Tool | Best for | Notable features | Main trade-off |
|---|---|---|---|
| HeaderSec | Best overall | Fast and deep scans, priority fixes, evidence, history, API | Newer than long-established scanners |
| MDN HTTP Observatory | Free second opinion | Header-focused scoring and actionable feedback | No detailed TLS or certificate testing |
| Hardenize | Continuous monitoring | Asset discovery, certificates, network and web configuration | Broader and more involved than a quick checker |
| ImmuniWeb | Broad website assessment | Headers, cookies, CSP, CMS, privacy, DNSSEC, compliance signals | More complex than a focused header report |
| Internet.nl | Internet standards | HTTPS, headers, DNSSEC, IPv6, RPKI, security.txt | Less focused on header-by-header remediation |
| OWASP ZAP | Self-hosting and CI | Passive and active scanning, Docker, API, automation framework | Requires setup and authorization to scan targets |
| Qualys SSL Labs | TLS configuration | Deep SSL/TLS analysis and browser simulations | Complements rather than replaces a header scanner |
1. HeaderSec — best overall SecurityHeaders.com alternative
HeaderSec is our top pick because it keeps the scan focused while providing more context for developers and operators. Enter a public URL, choose a fast or deep scan, and receive both a letter grade and a 0–100 header posture score. You can also bypass the cache when you need to confirm a recent configuration change.
The scanner checks controls related to HSTS, Content Security Policy, clickjacking, MIME sniffing, cookie attributes, cross-origin isolation, and avoidable information leakage. Results are separated into failed, warning, passed, and not-applicable groups. Instead of only listing missing headers, the report highlights priority fixes and includes evidence, remediation guidance, and reference links for individual findings.
HeaderSec also exposes useful request context. Reports show the requested and final URL, redirect chain, observed response headers, scan freshness, scanner version, and ruleset version. A shareable report link makes it easier to pass a finding to another developer or include it in a ticket.
For automation, the HeaderSec API supports bearer-token or x-headersec-api-key authentication. Authenticated scans are associated with a team and appear in dashboard history, while named keys can be created and revoked independently. A basic request looks like this:
export HEADERSEC_API_KEY="hsec_live_your_key_here"
curl -sS -X POST https://api.headersec.com/api/v1/scans \
-H "authorization: Bearer $HEADERSEC_API_KEY" \
-H "content-type: application/json" \
--data '{"url":"https://example.com","force":true}'
Choose HeaderSec if: you want a direct SecurityHeaders.com replacement with clearer prioritization, multiple scan depths, reproducible fresh scans, and an automation path for scripts or CI jobs.
2. MDN HTTP Observatory — best free second opinion
MDN HTTP Observatory, developed by Mozilla, analyzes HTTP headers and other important web security configurations. It produces a score and detailed test results, making it a valuable independent second opinion after changing CSP, HSTS, framing, referrer, or content-type policies.
The Observatory also has a versioned scan API, which is helpful for lightweight automation. Its scope is intentionally centered on HTTP data. Mozilla’s documentation notes that the current service does not provide specific TLS and certificate analysis, so pair it with SSL Labs when transport security is part of the review.
Choose MDN HTTP Observatory if: you want a respected, straightforward header assessment backed by Mozilla guidance.
3. Hardenize — best for continuous perimeter monitoring
Hardenize goes beyond a one-time header grade. Its platform combines Internet asset discovery with continuous monitoring of certificates, network services, and security configuration. Public reports inspect HTTPS deployment, redirects, returned HTTP headers, HSTS, Content Security Policy, and related web controls.
This broader scope is valuable for organizations with multiple domains, subdomains, cloud accounts, and certificates. It can help detect drift and expiring or newly discovered assets rather than waiting for someone to remember to run another manual scan.
Choose Hardenize if: you need ongoing visibility across an Internet-facing estate, not just an individual page check.
4. ImmuniWeb Website Security Test — best broader assessment
ImmuniWeb Website Security Test combines header analysis with a wider non-intrusive review. Its documented coverage includes CSP, HSTS, framing, MIME sniffing, referrer and permissions policies, CORS, cross-origin policies, cache controls, reporting endpoints, cookie flags, Subresource Integrity, DNSSEC, CMS components, and WAF detection.
The report also includes security, privacy, and compliance-oriented signals and can be exported as a PDF. That makes it useful when a stakeholder wants one broad artifact rather than a narrowly scoped header grade.
Choose ImmuniWeb if: you want HTTP header findings inside a wider website security and privacy assessment.
5. Internet.nl — best for modern Internet standards
Internet.nl evaluates whether a website supports modern Internet standards. Its website test covers HTTPS, HTTP security options and security.txt, DNSSEC, IPv6, and RPKI. Reports include an overall percentage score, results by test section, improvement guidance, and a permanent report URL.
It is especially useful when header security is only one part of an infrastructure modernization effort. Internet.nl also provides batch testing and a dashboard for multiple domains, although the presentation is less focused on detailed per-header remediation than HeaderSec.
Choose Internet.nl if: you want a standards-focused view spanning web, DNS, addressing, and routing.
6. OWASP ZAP — best self-hosted option for CI
OWASP ZAP is an open-source dynamic application security testing tool rather than a hosted header grader. Its passive rules can flag missing or weak security headers while traffic is proxied or a target is crawled. Packaged Docker scans, GitHub Actions, an API, and the Automation Framework make it suitable for repeatable testing in a delivery pipeline.
ZAP’s baseline scan performs passive checks, while full and API scans can perform active testing. Only run active scans against systems you own or have explicit permission to test. The extra setup is worthwhile when you need to combine header checks with broader application findings and control where results are stored.
Choose OWASP ZAP if: self-hosting, pipeline integration, configurable policies, or full web application testing matters more than instant hosted results.
7. Qualys SSL Labs — best companion for TLS analysis
Qualys SSL Labs Server Test performs deep analysis of a public SSL/TLS server. It examines protocol and cipher support, certificates, key exchange, known weaknesses, and compatibility across simulated clients. The familiar letter grade makes transport configuration easy to compare over time.
SSL Labs is not a complete replacement for SecurityHeaders.com because TLS configuration and browser security headers solve different problems. It belongs in this list because it is the strongest companion check when the goal is to assess the security of the full HTTPS connection rather than only the response headers.
Choose SSL Labs if: your main concern is certificate and TLS configuration, or use it alongside HeaderSec for a more complete review.
How to choose the right security header scanner
Start with the operational question you are trying to answer. If a developer just changed a CSP or reverse-proxy configuration, a focused scanner with an uncached rescan and concrete evidence is the fastest path. If you manage many domains, continuous discovery and monitoring may matter more than a polished single report. For release gates, favor a tool with documented API behavior and stable machine-readable output.
- For the closest all-around replacement: start with HeaderSec.
- For a second scoring opinion: run MDN HTTP Observatory.
- For continuous external monitoring: evaluate Hardenize.
- For a broader website and privacy review: use ImmuniWeb.
- For DNS, IPv6, routing, and web standards: use Internet.nl.
- For self-hosted testing and CI: deploy OWASP ZAP.
- For certificates, protocols, and ciphers: add SSL Labs.
Whichever tool you choose, test the actual production response after CDN, proxy, load balancer, and application behavior have been applied. A header present in source configuration may be removed, duplicated, or overridden before it reaches a browser.
What a header grade does not tell you
A strong grade is useful evidence of defense in depth, but it does not prove that a website is secure. Automated header scanners generally do not validate authorization rules, business logic, database access, secret handling, dependency risk, server patching, or every path through an application. They may also disagree about deprecated headers, acceptable CSP sources, or whether a policy is appropriate for a particular application.
Treat the report as a prioritized configuration review. Confirm each recommendation in a staging environment, especially CSP and cross-origin changes that can break legitimate scripts, frames, APIs, or authentication flows. Then combine header checks with TLS testing, dependency scanning, application testing, monitoring, and manual review appropriate to the risk of the system.
Our recommendation
For most teams seeking a SecurityHeaders.com alternative, HeaderSec is the best place to start. It is focused enough for a quick check but detailed enough to guide remediation, and its fast/deep modes, cache bypass, evidence, priority fixes, redirect inspection, dashboard history, and API give it room to grow with a team’s workflow.
Pair it with SSL Labs when TLS matters, or with OWASP ZAP when you need broader application testing. For the core task of understanding and improving HTTP security headers, HeaderSec offers the strongest balance of clarity, developer usability, and automation.
Frequently asked questions
What is the best SecurityHeaders.com alternative?
HeaderSec is our best overall pick because it combines a focused header grade with priority fixes, evidence, remediation guidance, fast and deep scan modes, uncached rescans, dashboard history, and authenticated API access.
Can a security header scanner find website vulnerabilities?
It can identify missing or weak browser-facing controls and some configuration problems. It cannot replace a vulnerability scan, penetration test, code review, or architecture review.
Which tool should I use for CI/CD?
HeaderSec provides an authenticated scan API for scripts and CI jobs. OWASP ZAP is the better fit when you want a self-hosted scanner with configurable passive and active policies inside your pipeline.