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

fsf.org

https://fsf.org· First analyzed 12 Feb 2026· Updated 12 Feb 2026

Export

fsf.org

Mobile

Sponsored

Hosting Provider

Hurricane Electric LLC

IP Address

209.51.188.174

Server Location

🇺🇸 Biddeford, United States

ASN

AS22989

Organization

Hurricane Electric LLC

Server

Nginx

CDN

Nameservers

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

Performance

Page Speed

52 KB

25 requests

0–49

50–89

90–100

Architecture Stack

Monolithic

⚙️ SSR

Infrastructure

Hosting

Hurricane Electric LLC

CDN

Technology Stack

3 Technologies Detected

CSS Frameworks

Tailwind CSS

Analytics

Matomo

Web Servers

Nginx

SEO Analysis

F35/100

fsf.orgfsf.org

Front Page — Free Software Foundation — working together for free s...

No description available for this page.

Title truncated.

Title Length74 chars

Recommended: 50-60 chars

Description Length0 chars

Recommended: 120-160 chars

Issues (2)

• Missing meta description - important for click-through rates
• Missing H1 tag - every page should have one H1

8 issues found

Upgrade to view details

Crawlability

Sitemap

Type: standard

212 URLs

robots.txt

100 rules

Sitemap reference found

Sponsored

Security Score

31%Critical

Interactive

HTTPS

No WAF

59d

Certificate Details

Type

Domain Validated (DV)

Certificate Authority

Let's Encrypt

Key Algorithm

RSA (2048 bit)

Signature

SHA-256 with RSA

TLS Version

TLSv1.2

HTTP Protocol

HTTP/1.0

Valid From

12.01.2026

Valid Until

12.04.2026

Subject Alternative Names (5)

*.fsf.org*.member.fsf.org*.members.fsf.org*.office.fsf.orgfsf.org

SHA-256 Fingerprint

34:5B:85:4C:B5:57:AB:FE:2B:D7:93:2E:7F:D6:B3:BD:60:C0:C2:FD...

Top Recommendations

Security recommendation preview

Upgrade to view recommendations

Upgrade to view header details

HTTP Headers

Developer Console

age

171

cache-control

🟡 0s(max-age=0, s-maxage=86400, must-revalidate)

connection

keep-alive

content-language

content-length

58276

content-type

text/html;charset=utf-8

Good Warning Issue

Email Infrastructure

Custom Mail Server

Score

SPF

DKIM

DMARC

DMARC Policy

None (Monitor Only)

MX Records (1)

mail.fsf.org

Domain Information

fsf.org

Domain Age

35 years

Created

01.02.1991

Expires

02.02.2027

Last Updated

09.12.2025

Registrar

Gandi SAS

DNSSEC

Not Enabled

Privacy & Compliance

Cookie Consent Banner

GDPR Indicators

Typography & Readability

sans-serif

33/100

Readability

/30

20/40

13px · LH 1.50

Hierarchy

/20

8/25

WCAG

/25

5/15

Contrast: undefined

Performance

/25

20/20

System fonts

Heading Font

sans-serif

Sans

Body Font

sans-serif

Sans13px

Contrast Ratio

Reading Comfort

~44 CPL

Needs attention

14px

15px

14px

13px

Minor Second

Scale

❌ Critical: 13px body text is too small. Increase to at least 14px.

✅ Optimal line spacing: 1.50 ratio ensures comfortable reading.

✅ Excellent performance: System fonts eliminate font loading delays (better LCP).

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

⚠️ Risky: Text appears on background images without overlay protection.

⚠️ Cramped layout: 36 elements lack adequate spacing.

Business & Marketing Stack

2 Tools Detected

Growing

Behavior Analytics

Matomo (Piwik)Mid-Market

Google AnalyticsFree

User behavior and product analytics

Sponsored

Scripts & Styles

4 Resources

Scripts

Styles

Async

Defer

Top Script Sources

piwik.fsf.org(1)

Sponsored

Last analyzed: 12 Feb 2026 at 13:44

Historical Analysis & Change Tracking