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.

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realpython.com

https://realpython.com· First analyzed 17 Feb 2026· Updated 17 Feb 2026

Export

realpython.com

Sponsored

Hosting Provider

Cloudflare

cloudflare.com

IP Address

172.66.152.40

Server Location

🇨🇦 Toronto, Canada

ASN

AS13335

Organization

Cloudflare, Inc.

Server

Cloudflare

CDN

Cloudflare

WAF

Cloudflare

Nameservers

curt.ns.cloudflare.com.joan.ns.cloudflare.com.

Performance

Page Speed

597 KB

36 requests

Image Optimization

Lazy LoadResponsive

0–49

50–89

90–100

Architecture Stack

Monolithic

⚙️ SSR

Frontend

Styling

Tailwind CSS

Infrastructure

Hosting

Cloudflare

CDN

Cloudflare

Progressive Web App

Web Manifest

Technology Stack

6 Technologies Detected

Libraries

Analytics

CSS Frameworks

CDN

SEO Analysis

A84/100

realpython.comrealpython.com

Python Tutorials – Real Python

Learn Python online: Python tutorials for developers of all skill levels, Python books and courses, Python news, code examples, articles, and more.

Title Length30 chars

Recommended: 50-60 chars

Description Length147 chars

Recommended: 120-160 chars

Issues (1)

• Missing H1 tag - every page should have one H1

1 issues found

Upgrade to view details

Crawlability

Sitemap

Type: standard

6,964 URLs

robots.txt

12 rules

Sitemap reference found

Allows all crawlers

Sponsored

Security Score

69%Fair

Interactive

HTTPS

WAF

82d

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+H3

Valid From

10.02.2026

Valid Until

11.05.2026

Subject Alternative Names (2)

*.realpython.comrealpython.com

SHA-256 Fingerprint

5F:94:5E:14:DE:43:3A:0F:D1:C3:AC:AD:E5:FF:54:65:E7:76:BB:CB...

Top Recommendations

Security recommendation preview

Upgrade to view recommendations

Upgrade to view header details

HTTP Headers

Developer Console

priority

u=0, i

content-type

text/html; charset=utf-8

cross-origin-opener-policy

same-origin

date

Tue, 17 Feb 2026 16:58:43 GMT

nel

{"report_to":"heroku-nel", "response_headers":["Via"], "max_...

referrer-policy

strict-origin-when-cross-origin

Good Warning Issue

Email Infrastructure

Google Workspace

Score

100

SPF

DKIM

DMARC

DMARC Policy

Reject (Strictest)

MX Records (5)

alt1.aspmx.l.google.com

alt4.aspmx.l.google.com

alt2.aspmx.l.google.com

aspmx.l.google.com

+1 more

Domain Information

realpython.com

Domain Age

13y 6m

Created

06.08.2012

Expires

06.08.2026

Last Updated

22.11.2025

Registrar

1API GmbH

DNSSEC

Not Enabled

Privacy & Compliance

Cookie Consent Banner

GDPR Indicators

Typography & Readability

-apple-system

69/100

Readability

/30

40/40

18px · LH 1.50

Hierarchy

/20

8/25

WCAG

/25

15/15

Contrast: undefined

Performance

/25

13/20

1 font

Heading Font

-apple-system

Sans

Body Font

-apple-system

Sans18px

Contrast Ratio

Reading Comfort

~41 CPL

Needs attention

32px

18px

✅ Excellent readability: 18px body text is ideal for all devices.

✅ Optimal line spacing: 1.50 ratio ensures comfortable reading.

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

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

✅ Smart font loading: Using font-display: swap prevents invisible text during load.

⚠️ Cramped layout: 56 elements lack adequate spacing.

Buy on MyFonts

Business & Marketing Stack

1 Tools Detected

Growing

Behavior Analytics

Google AnalyticsFree

User behavior and product analytics

Sponsored

Scripts & Styles

20 Resources

Scripts

Styles

Async

Defer

Top Script Sources

local(11)googletagmanager.com(1)srv.realpython.net(1)accounts.google.com(1)

Website Identity

Facebook X (Twitter)LinkedIn GitHub

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Last analyzed: 17 Feb 2026 at 16:59

Historical Analysis & Change Tracking