periodicsystem.org
Periodic System of The Elements
Last scanned Aug 5, 2026, 11:00 AM · 12 views
Overall score
Great
Summary
An accessible, extensible, interactive, and free periodic table of chemical elements, including the theoretical and beyond. This website uses Apache hosted on DREAMHOST-AS - New Dream Network, LLC, US. SEO is good (85/100) and accessibility is excellent (95/100). Security scores fair (65/100) and performance excellent (100/100). Top issue: No structured data (JSON-LD) found.
An accessible, extensible, interactive, and free periodic table of chemical elements, including the theoretical and beyond.
- United States
- Hosted on DREAMHOST-AS - New Dream Network, LLC, US
Top issues to fix
7 issues found · 3 high priority
Missing Strict-Transport-Security header
SecurityAdd HSTS so browsers always use HTTPS — this closes the protocol-downgrade attack window.
Missing Content-Security-Policy header
SecurityAdd a CSP to control which sources can run scripts — the strongest single defense against XSS.
Missing viewport meta tag
AccessibilityAdd <meta name="viewport" content="width=device-width, initial-scale=1"> — without it the site is broken on mobile.
Missing X-Content-Type-Options header
SecurityAdd X-Content-Type-Options: nosniff to stop MIME-sniffing attacks.
Missing X-Frame-Options header
SecurityAdd X-Frame-Options (or a CSP frame-ancestors rule) to prevent clickjacking via hidden iframes.
No structured data (JSON-LD) found
SEOAdd JSON-LD (Organization, Article, Product…) to become eligible for rich results.
+1 more issue — details in the sections below.
SEO
2 issue(s) found
Performance
339 ms
Security
HTTPS & header checks
Accessibility
1 issue(s) found
Score history
0 overall since Jul 26, 2026
- Overall
- 86
- SEO
- 85
- Security
- 65
- Performance
- 100
- Accessibility
- 95
Organization
Company details published in this site's own structured data.
An accessible, extensible, interactive, and free periodic table of chemical elements, including the theoretical and beyond.
Meta tags
- Title
- Periodic System of The Elements
- Description
- An accessible, extensible, interactive, and free periodic table of chemical elements, including the theoretical and beyond.
- Canonical
- https://periodicsystem.org/
- Language
- en
- Charset
- utf-8
- Viewport
- Robots meta
- follow,index,noarchive
- Manifest
Technologies
Detected frameworks, languages, and tools.
Hosting & CDN
- Hosting provider
- DREAMHOST-AS - New Dream Network, LLC, US
- CDN provider
- —
- IP address
- 75.119.206.244
- ASN
- AS26347 (DREAMHOST-AS - New Dream Network, LLC, US)
DNS records
| Type | Value |
|---|---|
| A |
|
| AAAA |
|
| MX |
|
| TXT |
|
| NS |
|
| CAA | — |
| CNAME | — |
| IPv6 support | Yes |
TLS / SSL certificate
- Version
- TLS 1.3
- Issuer
- Let's Encrypt
- Subject
- www.periodicsystem.org
- Valid from
- Jun 16, 2026
- Valid to
- Sep 14, 2026
- Days until expiry
- 39
- SAN domains
- periodicsystem.org, www.periodicsystem.org
Security headers
- Strict-Transport-SecurityMissing
- Content-Security-PolicyMissing
- X-Frame-OptionsMissing
- X-Content-Type-OptionsMissing
- Referrer-PolicyMissing
- Permissions-PolicyMissing
Compression: gzip · 0 cookie(s) observed
Content & assets
Headings
H1 1 · H2 0 · H3 0
Links
120 internal · 1 external · 0 broken
Images
0 total · 0 missing alt
Scripts / Styles
2 scripts · 1 stylesheets
JS / CSS size
720 B · 5.7 KB
Page size
63.7 KB
Robots.txt & Sitemap
- robots.txt
- Found
- Disallow rules
- 0
- sitemap.xml
- Not found
- URLs in sitemap
- 0
SEO issues
- No structured data (JSON-LD) found
- sitemap.xml not found
Accessibility issues
- Missing viewport meta tag
Scan details
- Requested URL
- https://periodicsystem.org
- Final URL
- https://periodicsystem.org
- HTTP status
- 200
- HTTP version
- HTTP/2
- Response time
- 338 ms
- HTML size
- 63.7 KB
- Redirect chain
- https://periodicsystem.org
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Frequently asked questions
- What technology does periodicsystem.org use?
- periodicsystem.org is built with Google Analytics, Apache.
- Is periodicsystem.org secure (HTTPS)?
- Yes. periodicsystem.org uses TLS 1.3 with a certificate issued by Let's Encrypt, valid until Sep 14, 2026.
- Who hosts periodicsystem.org?
- periodicsystem.org is hosted on DREAMHOST-AS - New Dream Network, LLC, US.
- What is periodicsystem.org's SEO score?
- periodicsystem.org scored 85/100 for SEO in the latest analysis (great).
- What is periodicsystem.org's overall website score?
- periodicsystem.org has an overall SiteGraph score of 86/100, combining SEO, performance, security, and accessibility.
- Has periodicsystem.org's score changed over time?
- periodicsystem.org's overall score has stayed steady at 86/100 since Jul 26, 2026.
OpenGraph & Twitter Card
OpenGraph
Twitter Card