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nbviewer.org

https://nbviewer.org· First analyzed 17 May 2026· Updated 17 May 2026
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nbviewer.org
Desktop screenshot of nbviewer.org
Mobile screenshot of nbviewer.org
Mobile

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Hosting Provider

Fastly, Inc.

IP Address

151.101.193.91

Site Location

🇨🇦 Canadavia ip

Server Location

🇨🇦 Montreal, Canada

ASN

AS54113

Organization

Fastly, Inc.

Server

TornadoServer/6.5.2

CDN

Fastly

Nameservers

marek.ns.cloudflare.com.vida.ns.cloudflare.com.

Performance

76

Core Web Vitals

Weight

First Contentful Paint
3.1 s10%
Speed Index
4.0 s10%
Largest Contentful Paint
—25%
Total Blocking Time
0.0 ms30%
Cumulative Layout Shift
0.00025%
1.1 MB
24 requests
0–49
50–89
90–100

Architecture Stack

Monolithic
⚙️ SSR
Frontend
Styling
Bootstrap
Infrastructure
Hosting
Fastly, Inc.
CDN
Fastly

Technology Stack

6 Technologies Detected

Libraries

2
jQuery
Moment.js

CSS Frameworks

2
Bootstrap
Tailwind CSS

Icon Libraries

1
Font Awesome

Analytics

1
Plausible Analytics

SEO Analysis

D50/100
15
9
3
Meta Tags4/15
Content8/12
Headings8/8
Technical12/25
E-E-A-T3/7
Images1/7
Links5/5
URL5/5
Social0/5
Freshness0/4
Mobile4/4
Indexability0/3
N
nbviewer.orgnbviewer.org

nbviewer

No description available for this page.

Title Length8 chars

Recommended: 50-60 chars (~50px / 580px)

Description Length0 chars

Recommended: 120-160 chars

Issues (3)

  • • Missing meta description — important for click-through rates in SERPs
  • • Most images missing alt text (12/12) — critical for accessibility and SEO
  • • Page is set to noindex — will not appear in search results

12 issues found

Upgrade to view details

Crawlability

Sitemap
robots.txt

6 rules

Local SEO

Local Search Readiness

3/100
Poor
1 14 2

This site doesn't appear to be a local business. Local SEO signals are optional for non-local websites.

Sponsored

AI & LLM Readiness

F33/100
Bot Access
20/25
Machine Read.
7/25
Schema Data
0/25
Citation
6/25

AI Bot Access

14/14 accessible
AI Search
OAI-SearchBot
PerplexityBot
Claude-SearchBot
Gemini-Deep-Research
DuckAssistBot
Training
GPTBot
ClaudeBot
Google-Extended
Meta-ExternalAgent
Bytespiderinfo
Amazonbot
Applebot-Extended
CCBotinfo
Fetch
ChatGPT-User

Machine Readability

llms.txt
llms-full.txt
Semantic HTML
Heading Hierarchy
navheader/footer
Text ratio:6%
Words:85
Token eff.:Too Short
Sections/1K:40
Depth:2/5

Structured Data

No Schema

Citation Readiness

Opening Summary12w
Descriptive Headingsavg 2.8w
Canonical URL
Open Graph0/3
Twitter Card0/3
Language Tag
Publish Date
Author Info
Lists
Tables
TL;DR / Summary
About Page Link
Recommendations (10)
AI readiness recommendation preview...
Upgrade to view recommendations

Sponsored

Accessibility

WCAG 2.1 Compliance

Evaluates how accessible your website is for users with disabilities, based on WCAG 2.1 guidelines. Checks images, forms, keyboard navigation, ARIA roles, and color contrast.
C
60/100
9
Passed
3
Critical
1
Warnings
Images & Alt Text
5/20
Checks if images have descriptive alt text for screen readers and visually impaired users.
Semantic Structure
20/20
Evaluates proper use of HTML5 semantic elements (header, nav, main, footer) and heading hierarchy.
Forms & Inputs
10/15
Verifies form fields have labels, error messages are clear, and inputs are properly associated.
Color & Contrast
15/15
Tests text-to-background color contrast ratios against WCAG AA/AAA minimum requirements.
Keyboard & Focus
9/15
Ensures all interactive elements are reachable and operable via keyboard (tab, enter, escape).
ARIA & Roles
1/15
Checks correct use of WAI-ARIA attributes (roles, states, properties) for assistive technologies.
3 recommendations
  • •Accessibility recommendation preview...
Upgrade to view recommendations

Carbon Footprint

SWDM v4 · Eco-Score

Carbon emissions estimated using the Sustainable Web Design Model v4 (SWDM v4). Factors in data center, network, and device energy across new and returning visitors. Grade thresholds based on HTTP Archive percentiles.
61/100
B
110 mg
CO₂e / view
1.1 MB
Page Weight
70%
Cleaner Than
New Visitor
126 mg
vs
Returning (cached)
63 mg
Annual (10K/mo)
13.2 kg
Emission Segments
Data Center
5 mg
Network
32 mg
Device
73 mg
Resource Breakdown
JavaScript
74.8 KB
Images
923.6 KB
CSS
90.9 KB
HTML
3.0 KB
Green Hosting Verified
Axis12 Ltd
GWF Verified
3 recommendations
  • •Carbon footprint recommendation preview...
Upgrade to view recommendations
D

Security Score

56%Poor
Interactive

HTTPS

No WAF

87d

Certificate Details

Type

Domain Validated (DV)

Certificate Authority

Let's Encrypt

Key Algorithm

RSA (2048 bit)

Signature

SHA-256 with RSA

TLS Version

TLSv1.3

HTTP Protocol

HTTP/2+H3

Valid From

14.05.2026

Valid Until

12.08.2026

Subject Alternative Names (1)

nbviewer.org

SHA-256 Fingerprint

AA:8B:64:2D:46:81:6C:C4:6E:48:33:00:4F:C4:92:FF:70:82:05:EE...

Top Recommendations

Security recommendation preview

Upgrade to view recommendations
Upgrade to view header details

HTTP Headers

Developer Console

accept-ranges
bytes
age
0
alt-svc
h3=":443";ma=86400,h3-29=":443";ma=86400,h3-27=":443";ma=864...
backend-name
6Bu2TkDGiFiZ92E9Blzx2E--F_ovh
content-encoding
📦 Gzip(gzip)
content-length
2738
Good Warning Issue

Email Infrastructure

Custom Mail Server

Score

0

SPF
DKIM
DMARC

Domain Information

nbviewer.org

Domain Age
13y 4m

Created

05.01.2013

Expires

05.01.2029

Last Updated

20.11.2025

Registrar

Key-Systems GmbH

DNSSEC
Not Enabled

Mobile Compatibility

Viewport & Responsive Test

Tests how well your website works on mobile devices. Checks viewport configuration, responsive layout, touch targets, font readability, and simulates rendering across different screen sizes.
C
62/100
Mobile Friendly1 breakpoint
Viewport Meta
The viewport meta tag tells mobile browsers how to scale the page. Without it, mobile devices render at desktop width.
Responsive Design
Uses CSS media queries or flexible layouts to adapt content to different screen sizes automatically.
Touch Icons
Apple touch icons and favicons displayed when users add the site to their home screen on mobile devices.
Readable Font Size
Base font size should be at least 16px on mobile to ensure text is readable without zooming.
Relative Units
Using em, rem, %, or vw instead of fixed px values allows content to scale properly across screen sizes.
No H-Scroll Risk
No elements wider than the viewport that would cause horizontal scrolling on mobile devices.
Tap Targets OK
Interactive elements (buttons, links) are at least 48x48px with enough spacing to prevent accidental taps.
No Fixed Widths
No elements with fixed pixel widths that could overflow on smaller screens and break the layout.
Viewport
width=device-width, initial-scale=1.0
2 recommendations
  • •Mobile compatibility recommendation preview...
Upgrade to view recommendations

Typography & Readability

Helvetica Neue

WCAG Partial
75/100
Readability
/30
18/30

14px · LH 1.43

Hierarchy
/20
18/20

5.79x ratio · ✓ H1→H6

WCAG
/25
17/25

2.15:1 min contrast

Performance
/25
22/25

System fonts

Heading Font

Helvetica Neue

Sans81px

Body Font

Helvetica Neue

Sans14px

Contrast Ratio

2.15:1

17 issues

Reading Comfort

~41 CPL

Narrow lines
81px
h1
30px
h2
24px
h3
14px
p

⚠️ Small text: 14px may strain on mobile. Use ≥16px for WCAG compliance.

✅ Optimal line spacing: 1.43 ratio (ideal range 1.4–1.6).

❌ Very complex text: Flesch score 8/100. Consider shorter sentences and simpler words.

⚠️ Partial contrast: 17 elements below WCAG AA threshold (min 2.1:1).

✅ Perfect heading hierarchy: Sequential h1→h2→h3 with single H1 — ideal for SEO & accessibility.

✅ Strong hierarchy: Headlines are 5.8x larger than body text.

Flesch 8

Color Palette

7 unique colors
2.91:1 Fail Light
#ffffff
Background· 89.7%
#9b9698
Other· 2.6%
#752b26
Primary· 2.5%
#d2d8db
Border· 1.5%

Business & Marketing Stack

2 Tools Detected

Growing

Behavior Analytics

2
PlausibleSMB
Google AnalyticsFree

User behavior and product analytics

1

Categories

2

Total Tools

0

Enterprise

0

Mid-Market

Assessment: Growing marketing technology adoption

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Scripts & Styles

10 Resources

7
Scripts
3
Styles
0
Async
1
Defer

Top Script Sources

local(6)plausible.io(1)

Website Identity

nbviewer.org

13 years old
Location detected: 🇨🇦 Canadavia ip
Key-Systems GmbHen

Social Profiles

GitHub

Sponsored

Last analyzed: 17 May 2026 at 00:51

Historical Analysis & Change Tracking