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

correios.com.br

https://correios.com.br· First analyzed 16 Feb 2026· Updated 16 Feb 2026

Export

correios.com.br

Mobile

Sponsored

Hosting Provider

Empresa Brasileira de Correios e Telégrafos

IP Address

201.48.198.80

Server Location

🇧🇷 Brasília, Brazil

ASN

AS16735

Organization

Empresa Brasileira de Correios e Telégrafos

CDN

Nameservers

ns3.correios.com.br.ns4.correios.com.br.ns1.correios.com.br.ns2.correios.com.br.

Performance

Page Speed

7.5 MB

145 requests

Image Optimization

Lazy Load

0–49

50–89

90–100

Architecture Stack

Monolithic

⚙️ SSR

Infrastructure

Hosting

Empresa Brasileira de Correios e Telégrafos

CDN

Technology Stack

7 Technologies Detected

Analytics

Meta Frameworks

Libraries

CSS Frameworks

Fonts

Tag Managers

SEO Analysis

C62/100

correios.com.brcorreios.com.br

Correios

Os Correios conectam você ao Brasil e ao mundo! Acesse nosso portal para rastrear encomendas, calcular fretes, conhecer serviços logísticos, postais e digita...

Description truncated.

Title Length8 chars

Recommended: 50-60 chars

Description Length186 chars

Recommended: 120-160 chars

Issues (1)

• Missing H1 tag - every page should have one H1

4 issues found

Upgrade to view details

Crawlability

Sitemap

robots.txt

15 rules

Sitemap reference found

Allows all crawlers

Sponsored

Security Score

20%Critical

Critical / Transactional

HTTPS

No WAF

221d

Certificate Details

Type

Domain Validated (DV)

Certificate Authority

DigiCert Inc

Key Algorithm

RSA (2048 bit)

Signature

SHA-256 with RSA

TLS Version

TLSv1.2

HTTP Protocol

HTTP/1.1

Valid From

11.09.2025

Valid Until

25.09.2026

OCSP Stapling

Enabled

Subject Alternative Names (2)

*.correios.com.brcorreios.com.br

SHA-256 Fingerprint

80:68:CD:CC:95:59:F6:E4:A9:3C:C4:B3:19:FE:72:80:F4:30:07:5C...

Top Recommendations

Security recommendation preview

Upgrade to view recommendations

Upgrade to view header details

HTTP Headers

Developer Console

accept-ranges

bytes

age

932

connection

keep-alive

content-encoding

📦 Gzip(gzip)

content-language

pt-br

content-type

text/html;charset=utf-8

Good Warning Issue

Email Infrastructure

Microsoft 365

Score

SPF

DKIM

DMARC

DMARC Policy

None (Monitor Only)

MX Records (1)

correios-com-br.mail.protection.outlook.com

Domain Information

correios.com.br

Domain Age

28y 3m

Created

30.10.1997

Expires

30.10.2028

Last Updated

18.05.2025

DNSSEC

Not Enabled

Privacy & Compliance

Cookie Consent Banner

Typography & Readability

Trebuchet MS

64/100

Readability

/30

40/40

16px · LH 1.50

Hierarchy

/20

21/25

2.25x ratio

WCAG

/25

5/15

Contrast: undefined

Performance

/25

13/20

1 font

Heading Font

Trebuchet MS

Sans36px

Body Font

Trebuchet MS

Sans16px

Contrast Ratio

Reading Comfort

~38 CPL

Needs attention

36px

22px

18px

16px

✅ Excellent readability: 16px body text is ideal for all devices.

✅ Optimal line spacing: 1.50 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.

⚠️ Risky: Text appears on background images without overlay protection.

Buy on MyFonts

Business & Marketing Stack

2 Tools Detected

Growing

Behavior Analytics

Google Tag ManagerFree

Google AnalyticsFree

User behavior and product analytics

Sponsored

Scripts & Styles

18 Resources

Scripts

Styles

Async

Defer

Top Script Sources

correios.com.br(5)googletagmanager.com(3)++theme++tema-do-portal-correios(3)google-analytics.com(1)local(1)

Website Identity

Facebook X (Twitter)Instagram LinkedIn TikTok

Sponsored

Last analyzed: 16 Feb 2026 at 15:57

Historical Analysis & Change Tracking