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codemirror.net

https://codemirror.net· First analyzed 25 Apr 2026· Updated 25 Apr 2026
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codemirror.net
Desktop screenshot of codemirror.net
Mobile screenshot of codemirror.net
Mobile

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Hosting Provider

TransIP BV

IP Address

149.210.142.219

Site Location

🇳🇱 Netherlandsvia ip

Server Location

🇳🇱 Amsterdam, The Netherlands

ASN

AS20857

Organization

TransIP BV

Server

Nginx

Nameservers

ns1.transip.nl.ns2.transip.eu.ns0.transip.net.

Performance

100

Core Web Vitals

Weight

First Contentful Paint
360 ms10%
Speed Index
468 ms10%
Largest Contentful Paint
—25%
Total Blocking Time
0.0 ms30%
Cumulative Layout Shift
0.00025%
648 KB
14 requests

Image Optimization

Lazy Load
0–49
50–89
90–100

Architecture Stack

Monolithic
⚙️ SSR
Cargo

Technology Stack

2 Technologies Detected

CSS Frameworks

1
Tailwind CSS

Web Servers

1
Nginxv1.26.3

SEO Analysis

D54/100
16
9
0
Meta Tags5/15
Content8/12
Headings8/8
Technical11/21
E-E-A-T0/7
Images5/7
Links5/5
URL5/5
Social3/5
Freshness0/4
Mobile1/4
Indexability3/3
C
codemirror.netcodemirror.net

CodeMirror

In-browser code editor

Title Length10 chars

Recommended: 50-60 chars (~62px / 580px)

Description Length22 chars

Recommended: 120-160 chars

Issues (0)

    9 issues found

    Upgrade to view details

    Local SEO

    Local Search Readiness

    4/100
    Poor
    2 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

    D41/100
    Bot Access
    20/25
    Machine Read.
    14/25
    Schema Data
    0/25
    Citation
    7/25

    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:13%
    Words:491
    Token eff.:Optimal
    Sections/1K:59.1
    Depth:2/5

    Structured Data

    No Schema

    Citation Readiness

    Opening Summary628w
    Descriptive Headingsavg 1.5w
    Canonical URL
    Open Graph3/3
    Twitter Card0/3
    Language Tag
    Publish Date
    Author Info
    Lists
    Tables
    TL;DR / Summary
    About Page Link
    Recommendations (9)
    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.
    A
    87/100
    14
    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
    20/20
    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
    11/15
    Ensures all interactive elements are reachable and operable via keyboard (tab, enter, escape).
    ARIA & Roles
    6/15
    Checks correct use of WAI-ARIA attributes (roles, states, properties) for assistive technologies.
    1 recommendation
    • •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.
    78/100
    A
    66 mg
    CO₂e / view
    648.2 KB
    Page Weight
    80%
    Cleaner Than
    New Visitor
    75 mg
    vs
    Returning (cached)
    37 mg
    Annual (10K/mo)
    7.9 kg
    Emission Segments
    Data Center
    3 mg
    Network
    19 mg
    Device
    43 mg
    Resource Breakdown
    JavaScript
    570.7 KB
    Images
    20.5 KB
    CSS
    52.8 KB
    HTML
    4.2 KB
    Green Hosting Verified
    Transip
    GWF Verified
    3 recommendations
    • •Carbon footprint recommendation preview...
    Upgrade to view recommendations
    B

    Security Score

    71%Good
    Static / Informational

    HTTPS

    No WAF

    56d

    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/1.1

    Valid From

    23.03.2026

    Valid Until

    21.06.2026

    Subject Alternative Names (3)

    codemirror.netdiscuss.codemirror.netlezer.codemirror.net

    SHA-256 Fingerprint

    F7:B4:DC:CD:A5:4A:83:F9:35:72:3C:39:69:57:EE:BD:39:16:AD:53...

    Recommendations

    Security recommendation preview

    Upgrade to view recommendations
    Upgrade to view header details

    HTTP Headers

    Developer Console

    connection
    keep-alive
    content-encoding
    📦 Gzip(gzip)
    content-type
    text/html; charset=utf-8
    date
    Sat, 25 Apr 2026 10:14:08 GMT
    etag
    W/"69e9bc5a-3253"
    last-modified
    Thu, 23 Apr 2026 06:29:46 GMT
    Good Warning Issue

    Email Infrastructure

    Custom Mail Server

    Score

    70

    SPF
    DKIM
    DMARC

    MX Records (1)

    mail.marijnhaverbeke.nl

    Domain Information

    codemirror.net

    Domain Age
    15y 8m

    Created

    03.08.2010

    Expires

    03.08.2026

    Last Updated

    02.12.2025

    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
    65/100
    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
    1 recommendation
    • •Mobile compatibility recommendation preview...
    Upgrade to view recommendations

    Typography & Readability

    Merriweather + Source Sans Pro

    WCAG Partial
    75/100
    Readability
    /30
    22/30

    16px · LH 1.45

    Hierarchy
    /20
    19/20

    2x ratio · ✓ H1→H6

    WCAG
    /25
    19/25

    3.84:1 min contrast

    Performance
    /25
    15/25

    2 fonts · 3 req

    Heading Font

    Merriweather

    Serif32px

    Body Font

    Source Sans Pro

    Sans16px

    Contrast Ratio

    3.84:1

    2 issues

    Reading Comfort

    ~41 CPL

    Narrow lines
    32px
    h1
    12px
    h2
    16px
    h3
    16px
    p

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

    ✅ Optimal line spacing: 1.45 ratio (ideal range 1.4–1.6).

    ⚠️ Hard to read: Flesch score 39/100. Simplify sentences for wider reach.

    ⚠️ Partial contrast: 2 elements below WCAG AA threshold (min 3.8:1).

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

    ✅ Strong hierarchy: Headlines are 2.0x larger than body text.

    Buy on MyFontsFlesch 39

    Color Palette

    8 unique colors
    5.82:1 AA Light
    #ffffff
    Background· 91.8%
    #656566
    Other· 1.3%

    Business & Marketing Stack

    1 Tools Detected

    Growing

    Behavior Analytics

    1
    Google AnalyticsFree

    User behavior and product analytics

    1

    Categories

    1

    Total Tools

    0

    Enterprise

    0

    Mid-Market

    Assessment: Growing marketing technology adoption

    Sponsored

    Scripts & Styles

    3 Resources

    2
    Scripts
    1
    Styles
    0
    Async
    2
    Defer

    Top Script Sources

    codemirror.js(1)demo.js(1)

    Website Identity

    codemirror.net

    15 years old
    Location detected: 🇳🇱 Netherlandsvia ip
    Key-Systems GmbHen-US

    Sponsored

    Last analyzed: 25 Apr 2026 at 10:14

    Historical Analysis & Change Tracking