Observatory
Test HTTP security headers such as CSP and HSTS, then review recommendations for improving a site.
About Observatory
Observatory is a free online tool from Mozilla that tests a website's HTTP security headers, including Content Security Policy (CSP) and HTTP Strict Transport Security (HSTS). It also assesses other key security configurations. After an automated scan, it gives recommendations for addressing potential vulnerabilities.
The tool launched in 2016. Its homepage states that it has provided insights to over 6.9 million websites through 47 million scans. Users can also test other websites to see how their configurations compare. The homepage does not describe usage limits or account requirements.
Key features
- Tests HTTP security headers, including Content Security Policy (CSP) and HSTS
- Assesses other key security configurations beyond HTTP headers
- Automated scanning of a website's security settings
- Provides recommendations for improving a site's security
- Allows comparison of test results with other websites
Best for: Developers and website administrators who want to check and improve the HTTP security configuration of their websites.
Good for
- Provides detailed, actionable feedback on identified security issues
- Automated scanning process requires no manual header inspection
Observatory at a glance
- Category
- Privacy & Security › Security Tools
- Type
- Website
- Pricing
- Not confirmed. Check the site
- Platforms
- Web
- Open source
- Not stated
- Language
- English
- Last checked
- Oct 6, 2026 · Online when checked
- Listed
- Oct 5, 2026
Guides for Security Tools
Observatory alternatives
Tools and sites you could use instead, ranked by how closely they match.
Clearstar reviews protocol governance, permissions, contracts, and oracles, then recommends fixes through its qualitative diligence process.
Use Metasploit to find security issues, verify mitigations, and manage authorized penetration testing assessments.
Agentic Radar scans agent workflows for security issues and helps developers review potential risks.
Open source
24 alternatives
ZeroSSL issues online SSL certificates and supports HTTPS setup through a certificate management interface.
Obtain a certificate for a website with Certbot, which helps configure HTTPS.
SSL for Free provides SSL and wildcard certificates for enabling HTTPS on websites.
Free
24 alternativesPopular in Security Tools
Well-known listings from the same topic.
Online Password Hash Crackonlinehashcrack.comOTP Authapps.apple.com/app/otp-auth/id659877384MD5 reverse lookupmd5.gromweb.comMozilla SSLssl-config.mozilla.orgchallenges.rechallenges.reGoPlus Locker V3gopluslabs.io
Observatory FAQ
What does the tool test?
It tests HTTP security headers such as CSP and HSTS, along with other key security configurations.
Can I test websites other than my own?
Yes. The homepage states that you can test other websites to see how they compare.
Is something wrong or out of date?
Tell us and an editor will check it.
Own this website?
Claim this listing
Claim the listing and suggest updates yourself. An editor checks every claim first.