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

fsfe.org

https://fsfe.org· First analyzed 20 Feb 2026· Updated 20 Feb 2026

Export

fsfe.org

Sponsored

Hosting Provider

Free Software Foundation Europe e.V.

IP Address

213.95.165.54

Server Location

🇩🇪 Frankfurt am Main, Germany

ASN

AS12337

Organization

Free Software Foundation Europe e.V.

Server

Apache

Nameservers

geoffroy.fsfeurope.org.tennant.fsfeurope.org.

Performance

Page Speed

2.6 MB

27 requests

0–49

50–89

90–100

Architecture Stack

Monolithic

⚙️ SSR

Infrastructure

Hosting

Free Software Foundation Europe e.V.

Technology Stack

5 Technologies Detected

Libraries

Other

CSS Frameworks

Icon Libraries

Web Servers

SEO Analysis

A80/100

fsfe.orgfsfe.org

FSFE - Free Software Foundation Europe

Non profit organisation working to create general understanding and support for software freedom. Includes news, events, and campaigns.

Title Length38 chars

Recommended: 50-60 chars

Description Length147 chars

Recommended: 120-160 chars

Issues (0)

3 issues found

Upgrade to view details

Crawlability

Sitemap

robots.txt

4 rules

Sponsored

Security Score

0%Critical

Critical / Transactional

HTTPS

No WAF

86d

Certificate Details

Type

Domain Validated (DV)

Certificate Authority

Let's Encrypt

Key Algorithm

ECDSA (secp256r1) (256 bit)

Signature

ECDSA with SHA-384

TLS Version

TLSv1.3

HTTP Protocol

HTTP/2

Valid From

16.02.2026

Valid Until

17.05.2026

Subject Alternative Names (4)

fsfe.orgfsfeurope.orgwww.fsfe.orgwww.fsfeurope.org

SHA-256 Fingerprint

C9:6E:B6:10:20:D5:7D:EE:90:39:B3:72:A4:D7:E7:E3:05:B2:B3:3B...

Top Recommendations

Security recommendation preview

Upgrade to view recommendations

Upgrade to view header details

HTTP Headers

Developer Console

accept-ranges

bytes

content-encoding

📦 Gzip(gzip)

content-language

content-length

5595

content-location

index.html.en

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 (2)

mail3.fsfe.org

mail2.fsfe.org

Domain Information

fsfe.org

Domain Age

24y 9m

Created

31.05.2001

Expires

31.05.2026

Last Updated

18.05.2025

Registrar

Gandi SAS

DNSSEC

Not Enabled

Privacy & Compliance

Cookie Consent Banner

GDPR Indicators

Typography & Readability

roboto

68/100

Readability

/30

40/40

16px · LH 1.43

Hierarchy

/20

18/25

2.25x ratio

WCAG

/25

5/15

Contrast: undefined

Performance

/25

20/20

System fonts

Heading Font

roboto

Sans36px

Body Font

roboto

Sans16px

Contrast Ratio

Reading Comfort

~38 CPL

Needs attention

36px

30px

24px

16px

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

✅ Optimal line spacing: 1.43 ratio ensures comfortable reading.

✅ Strong hierarchy: Headlines are 2.2x larger than body text.

✅ 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.

Business & Marketing Stack

1 Tools Detected

Growing

Behavior Analytics

Google AnalyticsFree

User behavior and product analytics

Sponsored

Scripts & Styles

5 Resources

Scripts

Styles

Async

Defer

Top Script Sources

local(3)

Website Identity

Mastodon

Sponsored

Last analyzed: 20 Feb 2026 at 09:47

Historical Analysis & Change Tracking