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

protonvpn.com

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

Export

protonvpn.com

Sponsored

Hosting Provider

ProtonVPN CH1

IP Address

185.159.159.140

Server Location

🇨🇭 Plan-les-Ouates, Switzerland

ASN

AS209103

Organization

ProtonVPN CH1

CDN

Cloudflare

WAF

Cloudflare

Nameservers

nora.ns.cloudflare.com.mitch.ns.cloudflare.com.

Performance

Page Speed

549 KB

196 requests

Image Optimization

Lazy LoadResponsive

0–49

50–89

90–100

Architecture Stack

Hybrid

⚙️ SSR

Frontend

Framework

Astro

Styling

Tailwind CSS

CMS

Ghost

Infrastructure

Hosting

ProtonVPN CH1

CDN

Cloudflare

Progressive Web App

Web ManifestApple Touch IconTheme Color

Technology Stack

3 Technologies Detected

Meta Frameworks

Astro

CSS Frameworks

Tailwind CSS

Analytics

FullStory

SEO Analysis

B78/100

protonvpn.comprotonvpn.com

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Title Length48 chars

Recommended: 50-60 chars

Description Length136 chars

Recommended: 120-160 chars

Issues (0)

4 issues found

Upgrade to view details

Crawlability

Sitemap

Type: index

22 URLs

robots.txt

4 rules

Sitemap reference found

Allows all crawlers

Sponsored

Security Score

61%Fair

Interactive

HTTPS

No WAF

59d

Certificate Details

Type

Domain Validated (DV)

Certificate Authority

Let's Encrypt

Key Algorithm

RSA (4096 bit)

Signature

SHA-256 with RSA

TLS Version

TLSv1.3

HTTP Protocol

HTTP/2

Valid From

17.01.2026

Valid Until

17.04.2026

Subject Alternative Names (10)

account.protonvpn.comapp.protonmail.chbeta.protonmail.commail.protonmail.comold.protonmail.compm.meprotonmail.chprotonmail.com+2 more

SHA-256 Fingerprint

82:C2:52:12:90:59:1C:86:EE:5B:0D:51:86:F9:B9:51:6E:D7:B9:15...

Top Recommendations

Security recommendation preview

Upgrade to view recommendations

Upgrade to view header details

HTTP Headers

Developer Console

accept-ranges

bytes

cache-control

🔴 No Cache(no-store, no-cache, must-revalidate, proxy-revalidate)

content-encoding

📦 Gzip(gzip)

content-length

48066

content-security-policy-report-only

default-src 'self'; media-src 'self'; connect-src 'self' htt...

content-type

text/html; charset=utf-8

Good Warning Issue

Email Infrastructure

Proton Mail

Score

SPF

DKIM

DMARC

DMARC Policy

Quarantine (Moderate)

MX Records (2)

mail.protonmail.ch

mail.proton.ch

Domain Information

protonvpn.com

Domain Age

9y 2m

Created

03.12.2016

Expires

03.12.2026

Last Updated

01.11.2024

Registrar

MarkMonitor Inc.

DNSSEC

Not Enabled

Privacy & Compliance

Cookie Consent Banner

GDPR Indicators

Typography & Readability

Arizona + Inter

71/100

Readability

/30

32/40

16px · LH 1.57

Hierarchy

/20

18/25

5.14x ratio

WCAG

/25

15/15

Contrast: undefined

Performance

/25

13/20

2 fonts

Heading Font

Arizona

Sans81px

Body Font

Inter

Sans16px

Contrast Ratio

Reading Comfort

~36 CPL

Needs attention

81px

54px

23px

16px

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

✅ Optimal line spacing: 1.57 ratio ensures comfortable reading.

✅ Strong hierarchy: Headlines are 5.1x larger than body text.

✅ Good performance: Using 2 font families keeps load times fast.

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

⚠️ Cramped layout: 108 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

2 Resources

Scripts

Styles

Async

Defer

Top Script Sources

local(1)

Website Identity

Facebook X (Twitter)Instagram LinkedIn TikTok Discord Telegram Reddit Threads Bluesky

Sponsored

Last analyzed: 17 Feb 2026 at 08:12

Historical Analysis & Change Tracking