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

cal.com

https://cal.com· First analyzed 14 Feb 2026· Updated 14 Feb 2026

Export

cal.com

Mobile

Sponsored

Hosting Provider

Cloudflare

cloudflare.com

IP Address

104.18.1.62

Server Location

🇨🇦 Toronto, Canada

ASN

AS13335

Organization

Cloudflare, Inc.

Server

Cloudflare

CDN

Cloudflare

WAF

Cloudflare

Nameservers

linda.ns.cloudflare.com.carter.ns.cloudflare.com.

Performance

Page Speed

669 KB

78 requests

Image Optimization

Lazy LoadWebPResponsive

0–49

50–89

90–100

Architecture Stack

Monolithic

⚙️ SSR

Framer

Progressive Web App

Web ManifestApple Touch Icon

Technology Stack

10 Technologies Detected

Analytics

CSS Frameworks

Icon Libraries

Fonts

Tag Managers

Advertising

Reviews

CDN

Customer Support

SEO Analysis

A80/100

cal.comcal.com

Cal.com | Open Scheduling Infrastructure

A fully customizable scheduling software for individuals, businesses taking calls and developers building scheduling platforms where users meet users.

Title Length40 chars

Recommended: 50-60 chars

Description Length150 chars

Recommended: 120-160 chars

Issues (1)

• Many images missing alt text (213/222)

2 issues found

Upgrade to view details

Crawlability

Sitemap

Type: standard

robots.txt

8 rules

Sponsored

Security Score

51%Poor

Interactive

HTTPS

WAF

40d

Certificate Details

Type

Domain Validated (DV)

Certificate Authority

Google Trust Services

Key Algorithm

ECDSA (secp256r1) (256 bit)

Signature

ECDSA with SHA-256

TLS Version

TLSv1.3

HTTP Protocol

HTTP/2

Valid From

26.12.2025

Valid Until

26.03.2026

OCSP Stapling

Enabled

Subject Alternative Names (2)

cal.com*.cal.com

SHA-256 Fingerprint

5A:CA:9B:74:D9:0F:4A:E9:AE:3B:12:C3:FA:0F:B7:86:C0:4F:4D:9F...

Top Recommendations

Security recommendation preview

Upgrade to view recommendations

Upgrade to view header details

HTTP Headers

Developer Console

cache-control

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

cf-cache-status

DYNAMIC

cf-ray🇩🇪 Frankfurt

9cdb3da78c1045e1-FRA

content-encoding

📦 Gzip(gzip)

content-type

text/html

date

Sat, 14 Feb 2026 08:36:58 GMT

Good Warning Issue

Email Infrastructure

Google Workspace

Score

SPF

DKIM

DMARC

DMARC Policy

Quarantine (Moderate)

MX Records (5)

alt1.aspmx.l.google.com

alt3.aspmx.l.google.com

alt2.aspmx.l.google.com

alt4.aspmx.l.google.com

+1 more

Domain Information

cal.com

Domain Age

28y 9m

Created

16.05.1997

Expires

17.05.2034

Last Updated

25.05.2024

Registrar

GoDaddy.com, LLC

DNSSEC

Not Enabled

Privacy & Compliance

Cookie Consent Banner

GDPR Indicators

Typography & Readability

Cal Sans + Cal Sans UI Light

76/100

Readability

/30

24/40

14px · LH 1.20

Hierarchy

/20

25/25

4.57x ratio

WCAG

/25

15/15

Contrast: undefined

Performance

/25

17/20

System fonts

Heading Font

Cal Sans

Sans64px

Body Font

Cal Sans UI Light

Sans14px

Contrast Ratio

Reading Comfort

~34 CPL

Needs attention

64px

48px

16px

14px

⚠️ Small text: 14px may be hard to read on mobile. Consider 16px+.

✅ Strong hierarchy: Headlines are 4.6x larger than body text.

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

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

✅ Protected text on images: Using gradient for readability.

⚠️ Cramped layout: 400 elements lack adequate spacing.

Buy on MyFonts

Business & Marketing Stack

5 Tools Detected

Enterprise

Behavior Analytics

PostHogMid-Market

Google Tag ManagerFree

Google AnalyticsFree

User behavior and product analytics

Advertising

Twitter/X AdsMid-Market

Ad platforms and retargeting pixels

Social Media

Twitter/X WidgetsFree

Social widgets and sharing tools

Sponsored

Scripts & Styles

6 Resources

Scripts

Styles

Async

Defer

Top Script Sources

eu-assets.i.posthog.com(1)ddwl4m2hdecbv.cloudfront.net(1)static.ads-twitter.com(1)dubcdn.com(1)events.framer.com(1)

Website Identity

GitHub

Sponsored

Last analyzed: 14 Feb 2026 at 08:37

Historical Analysis & Change Tracking