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.

Technology Comparison

Nlsn 2021 Blocks vs Yoast SEO

Side-by-side comparison based on real-world adoption data from 2,175 detections across analyzed websites.

Market Share Distribution

Nlsn 2021 Blocks (0%)Yoast SEO (100%)

Total Detections

Nlsn 2021 Blocks

2,174

Yoast SEO

HIGHER

Websites Using

Nlsn 2021 Blocks

2,174

Yoast SEO

HIGHER

Used Together

websites use both

0% OVERLAP

Nlsn 2021 Blocks

Plugins

1 detections

1 sites

View Profile

Yoast SEO

Plugins

Most popular WordPress SEO plugin with 5M+ active installs. Provides content analysis, XML sitemaps, schema markup, and readability checks.

2,174 detections

2174 sites

Visit Website View Profile

Our Analysis

Yoast SEO is significantly more popular than Nlsn 2021 Blocks in our dataset, appearing on 2174 websites compared to 1. 1 website uses both technologies together (0% overlap). Both are in the Plugins category, making them direct alternatives.

Sites Using Both (1)

nielsen.com

Only Nlsn 2021 Blocks

No exclusive sites found.

Only Yoast SEO

007.com 1-x.bet 10eurobonus.casino 123formbuilder.com 19fortyfive.com 1businessworld.com 1xbet-uz-sait.com 247wallst.com 24casinowin.com 24casinowin.net

Frequently Asked Questions

What is the difference between Nlsn 2021 Blocks and Yoast SEO?

Nlsn 2021 Blocks is a plugins technology. Most popular WordPress SEO plugin with 5M+ active installs. Provides content analysis, XML sitemaps, schema markup, and readability checks. Both belong to the Plugins category, making them direct alternatives.

Which is more popular, Nlsn 2021 Blocks or Yoast SEO?

Based on our analysis of real websites, Yoast SEO is more widely adopted with 2,174 detections compared to Nlsn 2021 Blocks's 1.

Can Nlsn 2021 Blocks and Yoast SEO be used together?

Yes! We've detected 1 website that use both Nlsn 2021 Blocks and Yoast SEO together, showing they can complement each other in certain setups.

Check Any Website's Technology Stack

Find out if a website uses Nlsn 2021 Blocks, Yoast SEO, or any other technology.

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