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jeroenjanssens.com

https://jeroenjanssens.com· First analyzed 04 Jun 2026· Updated 04 Jun 2026
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jeroenjanssens.com
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Mobile

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Hosting Provider

Cloudflare
cloudflare.com

IP Address

172.67.189.33

Site Location

🇨🇦 Canadavia ip

Server Location

🇨🇦 Toronto, Canada

ASN

AS13335

Organization

Cloudflare, Inc.

Server

Cloudflare

CDN

Cloudflare

WAF

Cloudflare

Nameservers

yahir.ns.cloudflare.com.roxy.ns.cloudflare.com.

Performance

100

Core Web Vitals

Weight

First Contentful Paint
600 ms10%
Speed Index
780 ms10%
Largest Contentful Paint
—25%
Total Blocking Time
0.0 ms30%
Cumulative Layout Shift
0.00025%
169 KB
17 requests
0–49
50–89
90–100

Architecture Stack

Monolithic
⚙️ SSR
Frontend
Styling
Tailwind CSS
Infrastructure
Hosting
Cloudflare
CDN
Cloudflare

Technology Stack

5 Technologies Detected

Frameworks

1
Alpine.js

CSS Frameworks

1
Tailwind CSS

Icon Libraries

1
Font Awesome

Email Marketing

1
ConvertKit

CDN

1
Cloudflare

SEO Analysis

C61/100
17
7
0
Meta Tags7/15
Content8/12
Headings8/8
Technical11/21
E-E-A-T3/7
Images4/7
Links5/5
URL5/5
Social3/5
Freshness0/4
Mobile4/4
Indexability3/3
J
jeroenjanssens.comjeroenjanssens.com

Jeroen Janssens

📛 I'm Jeroen (pronounced Yuh-ROON). Welcome to my site. 💻 I work at Posit, PBC as Head of Developer Relations. ✍️ Together with Thijs Nieuwdorp I wrote Pyt...

Description truncated.
Title Length15 chars

Recommended: 50-60 chars (~93px / 580px)

Description Length495 chars

Recommended: 120-160 chars

Issues (0)

    7 issues found

    Upgrade to view details

    Crawlability

    Sitemap

    Type: standard

    robots.txt

    Local SEO

    Local Search Readiness

    5/100
    Poor
    2 13 2

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

    Sponsored

    AI & LLM Readiness

    D46/100
    Bot Access
    20/25
    Machine Read.
    12/25
    Schema Data
    0/25
    Citation
    14/25

    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.txtinvalid
    llms-full.txt
    Semantic HTML
    Heading Hierarchy
    nav
    Text ratio:6%
    Words:215
    Token eff.:Too Short
    Sections/1K:14
    Depth:1/5

    Structured Data

    No Schema

    Citation Readiness

    Opening Summary30w
    Descriptive Headingsavg 1.7w
    Canonical URL
    Open Graph3/3
    Twitter Card0/3
    Language Tag
    Publish Date
    Author Info
    Lists
    Tables
    TL;DR / Summary
    About Page Link
    Recommendations (7)
    AI readiness recommendation preview...
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    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.
    B
    79/100
    11
    Passed
    2
    Critical
    0
    Warnings
    Images & Alt Text
    20/20
    Checks if images have descriptive alt text for screen readers and visually impaired users.
    Semantic Structure
    16/20
    Evaluates proper use of HTML5 semantic elements (header, nav, main, footer) and heading hierarchy.
    Forms & Inputs
    15/15
    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
    4/15
    Checks correct use of WAI-ARIA attributes (roles, states, properties) for assistive technologies.
    1 recommendation
    • •Accessibility recommendation preview...
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    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.
    74/100
    A+
    17 mg
    CO₂e / view
    169.0 KB
    Page Weight
    95%
    Cleaner Than
    New Visitor
    20 mg
    vs
    Returning (cached)
    10 mg
    Annual (10K/mo)
    2.1 kg
    Emission Segments
    Data Center
    <0.001 g
    Network
    5 mg
    Device
    11 mg
    Resource Breakdown
    JavaScript
    13.9 KB
    Images
    23.1 KB
    CSS
    43.4 KB
    Fonts
    82.1 KB
    HTML
    6.5 KB
    Green Hosting Verified
    Cloudflare
    GWF Verified
    3 recommendations
    • •Carbon footprint recommendation preview...
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    D

    Security Score

    41%Poor
    Interactive

    HTTPS

    WAF

    56d

    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+H3

    Valid From

    01.05.2026

    Valid Until

    30.07.2026

    OCSP Stapling

    Enabled

    Subject Alternative Names (1)

    jeroenjanssens.com

    SHA-256 Fingerprint

    9D:18:3C:A0:24:A3:B1:43:5A:8C:37:A2:33:D5:A0:0F:76:4A:02:42...

    Top Recommendations

    Security recommendation preview

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    Upgrade to view header details

    HTTP Headers

    Developer Console

    access-control-allow-origin
    *
    alt-svc
    h3=":443"; ma=86400
    cache-control
    🟡 0s(public, max-age=0, must-revalidate)
    cf-cache-status
    DYNAMIC
    cf-ray🇮🇹 Milan
    a064555ecc49edce-MXP
    content-encoding
    ⚡ Brotli(br)
    Good Warning Issue

    Email Infrastructure

    Google Workspace

    Score

    20

    SPF
    DKIM
    DMARC

    MX Records (5)

    alt2.aspmx.l.google.com
    alt4.aspmx.l.google.com
    alt3.aspmx.l.google.com
    alt1.aspmx.l.google.com

    +1 more

    Domain Information

    jeroenjanssens.com

    Domain Age
    21y 1m

    Created

    04.05.2005

    Expires

    04.05.2027

    Last Updated

    05.05.2026

    Registrar

    Realtime Register B.V.

    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.
    B
    73/100
    Mobile Friendly
    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, shrink-to-fit=no
    2 recommendations
    • •Mobile compatibility recommendation preview...
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    Typography & Readability

    IBM Plex Sans Condensed + IBM Plex Serif

    WCAG AA
    81/100
    Readability
    /30
    26/30

    18px · LH 1.78

    Hierarchy
    /20
    20/20

    2.67x ratio · ✓ H1→H6

    WCAG
    /25
    22/25

    5.93:1 min contrast

    Performance
    /25
    13/25

    2 fonts · 4 req

    Heading Font

    IBM Plex Sans Condensed

    Sans48px

    Body Font

    IBM Plex Serif

    Serif18px

    Contrast Ratio

    5.93:1

    WCAG AA (≥4.5:1)

    Reading Comfort

    ~39 CPL

    Narrow lines
    48px
    h1
    30px
    h2
    18px
    p

    ✅ Excellent readability: 18px body text is ideal for all devices.

    ✅ Easy to read: Flesch score 74/100 — accessible to general audiences.

    ✅ WCAG AA contrast: All text meets 4.5:1 ratio (min 5.9:1).

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

    ✅ Strong hierarchy: Headlines are 2.7x larger than body text.

    ✅ Lean font stack: 2 font families keeps load times fast.

    Buy on MyFontsFlesch 74

    Color Palette

    7 unique colors
    2.79:1 Fail Light
    #ffffff
    Background· 70.6%
    #8b9f9b
    Secondary· 2.7%
    #075f47
    Primary· 17.4%
    #c2b0a4
    Secondary· 3.1%
    #e9f1de
    Secondary· 1.8%
    #2e4e40
    Secondary· 1%

    Business & Marketing Stack

    2 Tools Detected

    Advanced

    Marketing Automation

    1
    ConvertKitCreator

    Email marketing and automation platforms

    Behavior Analytics

    1
    Google AnalyticsFree

    User behavior and product analytics

    2

    Categories

    2

    Total Tools

    0

    Enterprise

    0

    Mid-Market

    Assessment: Well-developed marketing technology stack

    Sponsored

    Scripts & Styles

    5 Resources

    4
    Scripts
    1
    Styles
    0
    Async
    4
    Defer

    Top Script Sources

    static.cloudflareinsights.com(2)f.convertkit.com(1)local(1)

    Website Identity

    jeroenjanssens.com

    [email protected]
    21 years old
    Location detected: 🇨🇦 Canadavia ip
    Realtime Register B.V.📧 Google Workspaceen

    Social Profiles

    LinkedInGitHubBluesky

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    Last analyzed: 04 Jun 2026 at 04:53

    Historical Analysis & Change Tracking