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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busuu.com

https://busuu.com· First analyzed 19 Feb 2026· Updated 19 Feb 2026

Export

busuu.com

Sponsored

Hosting Provider

Amazon Web Services (AWS)

aws.amazon.com

IP Address

13.33.235.124

Server Location

🇺🇸 New York, United States

ASN

AS16509

Organization

AWS CloudFront (GLOBAL)

Server

Envoy

CDN

CloudFront

Nameservers

ns-123.awsdns-15.com.ns-1422.awsdns-49.org.ns-1708.awsdns-21.co.uk.ns-801.awsdns-36.net.

Performance

Page Speed

437 KB

52 requests

Image Optimization

Lazy Load

0–49

50–89

90–100

Architecture Stack

Monolithic

⚙️ SSR

Infrastructure

Hosting

Amazon Web Services (AWS)

CDN

CloudFront

Progressive Web App

Web ManifestApple Touch Icon

Technology Stack

6 Technologies Detected

CSS Frameworks

Analytics

Tag Managers

Other

Reviews

SEO Analysis

A85/100

busuu.combusuu.com

Busuu - Learn Languages Online: Start for Free

Study a new language online with Busuu's award-winning courses. Learn together with native speakers in Busuu's community.

Title Length46 chars

Recommended: 50-60 chars

Description Length121 chars

Recommended: 120-160 chars

Issues (0)

2 issues found

Upgrade to view details

Crawlability

Sitemap

Type: index

15 URLs

robots.txt

22 rules

Sitemap reference found

Sponsored

Security Score

61%Fair

Interactive

HTTPS

No WAF

153d

Certificate Details

Type

Domain Validated (DV)

Certificate Authority

Amazon

Key Algorithm

RSA (2048 bit)

Signature

SHA-256 with RSA

TLS Version

TLSv1.3

HTTP Protocol

HTTP/2+H3

Valid From

23.06.2025

Valid Until

22.07.2026

OCSP Stapling

Enabled

Subject Alternative Names (4)

busuu.com*.busuu.com*.busuu.net*.internal.busuu.com

SHA-256 Fingerprint

49:FD:88:1D:A2:C4:85:4E:5E:90:26:B4:34:0D:12:47:71:2C:4F:CA...

Top Recommendations

Security recommendation preview

Upgrade to view recommendations

Upgrade to view header details

HTTP Headers

Developer Console

access-control-allow-credentials

true

access-control-allow-headers

Origin, X-Requested-With, Content-Type, Accept

access-control-allow-origin

https://www.busuu.com

age

4807

alt-svc

h3=":443"; ma=86400

cache-control

🔵 1 Week(max-age=604800)

Good Warning Issue

Email Infrastructure

Custom Mail Server

Score

100

SPF

DKIM

DMARC

DMARC Policy

Reject (Strictest)

MX Records (2)

mxa-00360d01.gslb.pphosted.com

mxb-00360d01.gslb.pphosted.com

Domain Information

busuu.com

Domain Age

18y 4m

Created

18.10.2007

Expires

18.10.2027

Last Updated

17.09.2025

Registrar

MarkMonitor Inc.

DNSSEC

Not Enabled

Privacy & Compliance

Cookiebot

Cookie Consent Banner

Cookiebot

GDPR Indicators

Cookie consent banner detected

CMP: Cookiebot

Data Protection Officer mentioned

Typography & Readability

Nista

83/100

Readability

/30

40/40

18px · LH 1.70

Hierarchy

/20

25/25

2.22x ratio

WCAG

/25

15/15

Contrast: undefined

Performance

/25

13/20

1 font

Heading Font

Nista

Sans40px

Body Font

Nista

Sans18px

Contrast Ratio

Reading Comfort

~40 CPL

Needs attention

40px

24px

18px

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

✅ Optimal line spacing: 1.70 ratio ensures comfortable reading.

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

✅ 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.

Buy on MyFonts

Business & Marketing Stack

6 Tools Detected

Enterprise

Behavior Analytics

Google Tag ManagerFree

Google AnalyticsFree

User behavior and product analytics

Privacy & Cookies

OneTrustEnterprise

Cookie consent and privacy compliance tools

Social Media

Facebook SDKFree

Social widgets and sharing tools

A/B Testing & Optimization

OptimizelyEnterprise

Experimentation and conversion optimization

Reviews & Social Proof

TrustpilotMid-Market

Customer reviews and testimonials

Sponsored

Scripts & Styles

8 Resources

Scripts

Styles

Async

Defer

Top Script Sources

cdn.busuu.com(2)googletagmanager.com(1)geolocation.onetrust.com(1)cdn.cookielaw.org(1)accounts.google.com(1)

Website Identity

busuu.com

18 years old

MarkMonitor Inc.

Social Profiles

Facebook X (Twitter)YouTube TikTok

Sponsored

Last analyzed: 19 Feb 2026 at 14:10

Historical Analysis & Change Tracking