DomainOptic vs Mozilla Observatory: Honest Comparison (2026)
Published January 29, 2026 - 7 min read
TL;DR: Mozilla Observatory is backed by Mozilla and focuses on HTTP security headers with strict, CSP-heavy scoring. DomainOptic covers more ground: SSL, DNS, headers, blacklists, and secret scanning in one scan. Use Observatory for Mozilla's security recommendations, DomainOptic for comprehensive security checks.
Quick Comparison
| Feature |
DomainOptic |
Mozilla Observatory |
| Security Headers Check |
Yes |
Yes (stricter scoring) |
| CSP Analysis |
Basic |
Detailed |
| SSL/TLS Certificate Check |
Yes |
No (links to SSL Labs) |
| DNS Health Check |
Yes |
No |
| Email Auth (SPF/DKIM/DMARC) |
Yes |
No |
| Blacklist Check |
Yes |
No |
| Secret/API Key Scanner |
Yes |
No |
| Third-Party Test Integration |
No |
Yes (SSL Labs, ImmuniWeb) |
| Open Source |
No |
Yes |
| Signup Required |
No |
No |
| Price |
Free |
Free |
About Mozilla Observatory
Mozilla Observatory (observatory.mozilla.org) is built by Mozilla, the organization behind Firefox. It's open source and reflects Mozilla's security recommendations for websites.
The tool checks HTTP security headers and gives you a score from 0 to 100 (translated to letter grades). The scoring is opinionated: it heavily rewards Content Security Policy (CSP) and penalizes sites without one.
Mozilla Observatory checks:
- Content-Security-Policy
- Cookies (Secure, HttpOnly, SameSite)
- Cross-Origin Resource Sharing
- Referrer-Policy
- Strict-Transport-Security
- Subresource Integrity
- X-Content-Type-Options
- X-Frame-Options
It also links to third-party scanners like SSL Labs and ImmuniWeb for additional tests.
About DomainOptic
DomainOptic is a comprehensive security audit tool. One scan checks multiple security aspects:
- SSL certificate status and expiration
- DNS health and configuration
- Email authentication (SPF, DKIM, DMARC)
- Security headers with letter grade
- Blacklist status
- Exposed secrets in JavaScript
Our header scoring is less strict than Mozilla's. We check whether you have the important headers; Observatory judges how well they're configured.
When to Use Mozilla Observatory
Mozilla Observatory is the better choice when:
- You want Mozilla's specific recommendations: They have strong opinions about security headers, especially CSP. Following their guidance is reasonable.
- You're implementing CSP: Observatory gives detailed feedback on CSP configuration.
- You want the integrated view: Links to SSL Labs and other tools from one page.
- You care about open source: Observatory's code is public. You can see exactly how it scores.
- You're aiming for a specific grade: Some organizations target "A" grades on Observatory specifically.
When to Use DomainOptic
DomainOptic is the better choice when:
- You want a complete security picture: SSL, DNS, headers, blacklists, and secrets in one scan.
- You need to check email authentication: SPF, DKIM, DMARC matter for deliverability. Observatory doesn't check these.
- You're checking for exposed API keys: Our Secret Scanner finds credentials in JavaScript. Observatory doesn't do this.
- You find Observatory's scoring too strict: Many legitimate sites score D or F on Observatory because they don't have extensive CSP. Our scoring is more practical.
- You want results without clicking through to other tools: One scan, one report.
Honest Assessment: Where Mozilla Observatory Wins
We respect what Mozilla built. Here's where Observatory is better:
- Mozilla's backing: Built by the Firefox team. Their security recommendations carry weight.
- CSP expertise: Detailed CSP analysis and guidance. They really care about Content Security Policy.
- Open source: You can inspect the code, understand the scoring, even run it yourself.
- Third-party integration: Links to SSL Labs, ImmuniWeb, and other scanners from one interface.
- Cookie analysis: Checks Secure, HttpOnly, and SameSite attributes specifically.
Honest Assessment: Where DomainOptic Wins
- Comprehensive coverage: SSL, DNS, email auth, headers, blacklists, secrets. Observatory only does headers.
- Secret scanning: We check for exposed API keys in JavaScript. This is a real vulnerability that Observatory ignores.
- Email authentication: SPF, DKIM, DMARC checks. Critical for 2026.
- Practical scoring: Observatory's strict CSP requirements mean many good sites score poorly. Our scoring is more balanced.
- One report: You don't need to click through to multiple tools.
A Note on Scoring Differences
You might score very differently on DomainOptic vs Mozilla Observatory. Here's why:
Observatory heavily weights Content Security Policy. A site with perfect headers but no CSP will score poorly. This is a deliberate choice: Mozilla believes CSP is critical.
DomainOptic takes a more balanced approach. We check if you have important headers. A missing CSP hurts your score but doesn't tank it.
Neither approach is wrong. Observatory reflects Mozilla's security philosophy. DomainOptic reflects a more pragmatic view of what most sites actually need.
Using Both Tools
A reasonable workflow:
- Run DomainOptic for a complete security overview: SSL, DNS, headers, secrets
- If your headers need work, run Mozilla Observatory for detailed guidance
- If implementing CSP, use Observatory iteratively as you refine your policy
Frequently Asked Questions
What is the difference between DomainOptic and Mozilla Observatory?
Mozilla Observatory focuses on HTTP security headers with strict, opinionated scoring that emphasizes Content Security Policy. DomainOptic is an all-in-one scanner that checks headers plus SSL, DNS, email authentication, blacklist status, and exposed secrets in JavaScript.
Why is my Mozilla Observatory score so low?
Mozilla Observatory has strict scoring that heavily weights Content Security Policy (CSP). Sites without a strong CSP often score D or F even if other headers are correct. The scoring reflects Mozilla's security recommendations, which prioritize CSP more than some other tools.
Is Mozilla Observatory free?
Yes, Mozilla Observatory is completely free and open source. DomainOptic is also free with no signup required for basic scans.
Does Mozilla Observatory check for exposed API keys?
No, Mozilla Observatory only checks HTTP security headers. DomainOptic includes a Secret Scanner that detects exposed API keys (AWS, Stripe, OpenAI, etc.) in your public JavaScript files.
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