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

seld.be

https://seld.be· First analyzed 17 Feb 2026· Updated 17 Feb 2026

Export

seld.be

Sponsored

Hosting Provider

GitHub Pages

pages.github.com

IP Address

185.199.110.153

Server Location

🇺🇸 San Francisco, United States

ASN

AS54113

Organization

GitHub, Inc

Server

GitHub.com

CDN

Fastly

Nameservers

ns106.ovh.net.dns106.ovh.net.

Performance

Page Speed

83 KB

7 requests

0–49

50–89

90–100

Architecture Stack

Monolithic

⚙️ SSR

Frontend

Styling

Tailwind CSS

Infrastructure

Hosting

GitHub Pages

CDN

Fastly

Technology Stack

4 Technologies Detected

Analytics

CSS Frameworks

Fonts

SEO Analysis

C64/100

seld.beseld.be

Jordi's Ramblings

Notes about PHP, Open Source and perhaps more

Title Length17 chars

Recommended: 50-60 chars

Description Length45 chars

Recommended: 120-160 chars

Issues (0)

5 issues found

Upgrade to view details

Crawlability

Sitemap

Type: standard

82 URLs

robots.txt

Sponsored

Security Score

21%Critical

Interactive

HTTPS

No WAF

32d

Certificate Details

Type

Domain Validated (DV)

Certificate Authority

Let's Encrypt

Key Algorithm

RSA (2048 bit)

Signature

SHA-256 with RSA

TLS Version

TLSv1.3

HTTP Protocol

HTTP/2

Valid From

21.12.2025

Valid Until

21.03.2026

Subject Alternative Names (2)

seld.bewww.seld.be

SHA-256 Fingerprint

B3:73:4C:8C:EC:0D:DA:82:BA:EC:CB:4D:B9:0A:59:CB:9C:F3:3A:8A...

Top Recommendations

Security recommendation preview

Upgrade to view recommendations

Upgrade to view header details

HTTP Headers

Developer Console

accept-ranges

bytes

access-control-allow-origin

age

cache-control

🟡 600s(max-age=600)

content-encoding

📦 Gzip(gzip)

content-length

3719

Good Warning Issue

Email Infrastructure

Google Workspace

Score

SPF

DKIM

DMARC

DMARC Policy

Quarantine (Moderate)

MX Records (7)

aspmx2.googlemail.com

aspmx3.googlemail.com

alt2.aspmx.l.google.com

alt1.aspmx.l.google.com

+3 more

Domain Information

seld.be

DNSSEC

Not Enabled

Privacy & Compliance

Cookie Consent Banner

GDPR Indicators

Data Protection Officer mentioned

Typography & Readability

ui-sans-serif

78/100

Readability

/30

40/40

17px · LH 1.60

Hierarchy

/20

15/25

1.41x ratio

WCAG

/25

15/15

Contrast: undefined

Performance

/25

13/20

1 font

Heading Font

ui-sans-serif

Sans24px

Body Font

ui-sans-serif

Sans17px

Contrast Ratio

Reading Comfort

~35 CPL

Needs attention

24px

28px

17px

Minor Third

Scale

✅ Excellent readability: 17px body text is ideal for all devices.

✅ Optimal line spacing: 1.60 ratio ensures comfortable reading.

⚠️ Weak hierarchy: Headlines should be at least 2x body size for clear visual structure.

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

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

⚠️ Cramped layout: 10 elements lack adequate spacing.

GGoogle Fonts

Business & Marketing Stack

2 Tools Detected

Growing

Behavior Analytics

Google AnalyticsFree

Google Tag ManagerFree

User behavior and product analytics

Sponsored

Scripts & Styles

4 Resources

Scripts

Styles

Async

Defer

Top Script Sources

googletagmanager.com(1)local(1)

Website Identity

X (Twitter)GitHub Mastodon

Sponsored

Last analyzed: 17 Feb 2026 at 04:09

Historical Analysis & Change Tracking