What does StackOptic analyze?

StackOptic runs 18 analysis modules on any public website from a single URL. It detects 7,000+ technologies (CMS, frameworks, analytics, payments, CDN, hosting), evaluates SSL certificates and HTTP security headers with grades from A+ to F, measures Core Web Vitals (LCP, CLS, TBT, FCP), audits SEO meta tags and structured data, checks email security (SPF, DKIM, DMARC), analyzes AI & LLM readiness including bot access and llms.txt validation, extracts color palettes and typography, estimates carbon footprint, and generates permanent shareable reports.

Does it work on sites behind Cloudflare or bot protection?

Yes. StackOptic uses a real browser engine that loads pages exactly like a human visitor — executing JavaScript, rendering CSS, and handling redirects. This allows it to bypass Cloudflare, LiteSpeed, Sucuri, and other bot protection systems where traditional crawlers and HTTP-only tools fail.

What do I get on the free plan?

The free plan includes 5 analyses per day with access to all 18 modules, full scores, technology detection, and security grades. Every report is permanently accessible via a unique shareable URL — no login required to view. No credit card needed. AI-powered insights, re-analysis, PDF/JSON export, and comparison features are available on Pro ($24/mo) and Agency ($99/mo) plans.

What is AI & LLM readiness analysis?

This module evaluates how visible and citable your website is to AI search engines like ChatGPT, Perplexity, Google AI Overviews, and Claude. It audits access permissions for 8 major AI bots, validates llms.txt and llms-full.txt files, scores citation-ready content structure, and analyzes structured data (JSON-LD) for GEO readiness — helping you rank in the next generation of search.

How long does an analysis take?

Most analyses complete in under 10 seconds. StackOptic runs all 18 modules in parallel using a real browser session, so you get technology detection, security audit, performance metrics, SEO analysis, and AI readiness scoring simultaneously.

How accurate are the results?

Detection is based on real browser execution — DOM inspection, JavaScript runtime analysis, HTTP headers, and DNS records. With 7,000+ technology signatures and Lighthouse-calibrated performance scoring, StackOptic achieves high accuracy for mainstream technologies.

What security checks are performed?

The security module evaluates SSL/TLS certificates, 12+ HTTP security headers (HSTS, CSP, X-Frame-Options, Permissions-Policy, Referrer-Policy), HTTPS enforcement, and email authentication (SPF, DKIM, DMARC). Each site receives a letter grade from A+ to F with specific remediation steps.

Do you store the websites I analyze?

StackOptic only stores publicly available information that any visitor to a website would see — HTML content, HTTP headers, DNS records, and screenshots. We do not access private data, log in to websites, or perform any intrusive testing.

Back to Search

gnu.org

https://gnu.org· First analyzed 10 Feb 2026· Updated 10 Feb 2026

Export

gnu.org

Mobile

Sponsored

Hosting Provider

Hurricane Electric LLC

IP Address

209.51.188.116

Server Location

🇺🇸 Biddeford, United States

ASN

AS22989

Organization

Hurricane Electric LLC

Server

Apache

Nameservers

ns1.gnu.org.ns2.gnu.org.ns4.gnu.org.

Performance

Page Speed

174 KB

18 requests

0–49

50–89

90–100

Architecture Stack

Monolithic

⚙️ SSR

Infrastructure

Hosting

Hurricane Electric LLC

Technology Stack

2 Technologies Detected

CSS Frameworks

Tailwind CSS

Web Servers

Apache

SEO Analysis

D58/100

gnu.orggnu.org

The GNU Operating System and the Free Software Movement

Since 1983, developing the free Unix style operating system GNU, so that computer users can have the freedom to share and improve the software they use.

Title Length55 chars

Recommended: 50-60 chars

Description Length152 chars

Recommended: 120-160 chars

Issues (1)

• Missing H1 tag - every page should have one H1

5 issues found

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Security Score

56%Poor

Interactive

HTTPS

No WAF

57d

Top Recommendations

Security recommendation preview

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HTTP Headers

Developer Console

accept-ranges

bytes

access-control-allow-origin

(null)

cache-control

🟡 0s(max-age=0)

connection

Keep-Alive

content-encoding

📦 Gzip(gzip)

content-language

Good Warning Issue

Typography & Readability

Times New Roman

54/100

Readability

/30

25/40

16px · LH 1.00

Hierarchy

/20

8/25

WCAG

/25

15/15

Contrast: undefined

Performance

/25

13/20

1 font

Heading Font

Times New Roman

Serif

Body Font

Times New Roman

Serif16px

Contrast Ratio

Reading Comfort

~40 CPL

Needs attention

32px

22px

16px

✅ Excellent readability: 16px body text is ideal for all devices.

⚠️ Tight line spacing (1.00). Consider 1.4-1.6 for better readability.

✅ Good performance: Using 1 font families keeps load times fast.

✅ Consistent design: Single font family with weight variations is a modern best practice.

✅ Protected text on images: Using gradient for readability.

⚠️ Cramped layout: 9 elements lack adequate spacing.

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Business & Marketing Stack

1 Tools Detected

Growing

Behavior Analytics

Google AnalyticsFree

User behavior and product analytics

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Scripts & Styles

2 Resources

Scripts

Styles

Async

Defer

Top Script Sources

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Last analyzed: 10 Feb 2026 at 18:56

Historical Analysis & Change Tracking