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reactivex.io

https://reactivex.io· First analyzed 02 May 2026· Updated 02 May 2026
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reactivex.io
Desktop screenshot of reactivex.io
Mobile screenshot of reactivex.io
Mobile

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Hosting Provider

GitHub Pages
pages.github.com

IP Address

185.199.108.153

Site Location

🇺🇸 United Statesvia ip

Server Location

🇺🇸 San Francisco, United States

ASN

AS54113

Organization

GitHub, Inc

Server

GitHub.com

CDN

Fastly

Nameservers

ns2.hover.com.ns1.hover.com.

Performance

100

Core Web Vitals

Weight

First Contentful Paint
504 ms10%
Speed Index
655 ms10%
Largest Contentful Paint
—25%
Total Blocking Time
0.0 ms30%
Cumulative Layout Shift
0.00025%
1.1 MB
53 requests
0–49
50–89
90–100

Architecture Stack

Monolithic
⚙️ SSR
Frontend
Styling
Bootstrap
Infrastructure
Platform
GitHub Pages
CDN
Fastly

Technology Stack

3 Technologies Detected

CSS Frameworks

2
Bootstrap
Tailwind CSS

Libraries

1
jQueryv1.11.0

SEO Analysis

D49/100
13
9
1
Meta Tags4/15
Content10/12
Headings6/8
Technical10/21
E-E-A-T0/7
Images2/7
Links5/5
URL5/5
Social0/5
Freshness0/4
Mobile4/4
Indexability3/3
R
reactivex.ioreactivex.io

ReactiveX

No description available for this page.

Title Length9 chars

Recommended: 50-60 chars (~53px / 580px)

Description Length0 chars

Recommended: 120-160 chars

Issues (1)

  • • Missing meta description — important for click-through rates in SERPs

10 issues found

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Local SEO

Local Search Readiness

6/100
Poor
2 13 2

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

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AI & LLM Readiness

F31/100
Bot Access
20/25
Machine Read.
3/25
Schema Data
0/25
Citation
8/25

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
Text ratio:12%
Words:293
Token eff.:Too Short
Sections/1K:41

Structured Data

No Schema

Citation Readiness

Opening Summary18w
Descriptive Headingsavg 4w
Canonical URL
Open Graph0/3
Twitter Card0/3
Language Tag
Publish Date
Author Info
Lists
Tables
TL;DR / Summary
About Page Link
Recommendations (12)
AI readiness recommendation preview...
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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
73/100
9
Passed
4
Critical
0
Warnings
Images & Alt Text
20/20
Checks if images have descriptive alt text for screen readers and visually impaired users.
Semantic Structure
11/20
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
3/15
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.
44/100
B
136 mg
CO₂e / view
1.1 MB
Page Weight
70%
Cleaner Than
New Visitor
156 mg
vs
Returning (cached)
78 mg
Annual (10K/mo)
16.4 kg
Emission Segments
Data Center
30 mg
Network
33 mg
Device
73 mg
Resource Breakdown
JavaScript
280.3 KB
Images
25.1 KB
CSS
793.0 KB
HTML
4.1 KB
Green Hosting Not Verified
GitHub Pages
3 recommendations
  • •Carbon footprint recommendation preview...
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B

Security Score

71%Good
Static / Informational

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

Valid From

29.04.2026

Valid Until

28.07.2026

Subject Alternative Names (2)

reactivex.iowww.reactivex.io

SHA-256 Fingerprint

4A:C2:BE:1C:CC:CD:55:25:57:8B:6A:30:47:81:3E:DB:D5:53:A7:33...

Recommendations

Security recommendation preview

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HTTP Headers

Developer Console

accept-ranges
bytes
access-control-allow-origin
*
age
0
cache-control
🟡 600s(max-age=600)
content-encoding
📦 Gzip(gzip)
content-length
3883
Good Warning Issue

Email Infrastructure

Custom Mail Server

Score

0

SPF
DKIM
DMARC

Domain Information

reactivex.io

Domain Age
12y 4m

Created

04.01.2014

Expires

04.01.2027

Last Updated

04.12.2025

Registrar

Tucows Domains Inc.

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.
D
57/100
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
2 recommendations
  • •Mobile compatibility recommendation preview...
Upgrade to view recommendations

Typography & Readability

Helvetica

WCAG Partial
66/100
Readability
/30
25/30

16px · LH 1.43

Hierarchy
/20
14/20

4.5x ratio

WCAG
/25
16/25

1:1 min contrast

Performance
/25
11/25

3 fonts · 3 req

Heading Font

Helvetica

Sans72px

Body Font

Helvetica

Sans16px

Contrast Ratio

1:1

16 issues

Reading Comfort

~36 CPL

Narrow lines
72px
h1
28px
h2
24px
h3
20px
h4
16px
p

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

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

❌ Very complex text: Flesch score 20/100. Consider shorter sentences and simpler words.

⚠️ Partial contrast: 16 elements below WCAG AA threshold (min 1.0:1).

⚠️ Minor heading issue: 0 level skip(s) detected. Maintain sequential order for screen readers.

✅ Strong hierarchy: Headlines are 4.5x larger than body text.

Buy on MyFontsFlesch 20

Color Palette

6 unique colors
Light
#95808a
Secondary· 5%
#20141d
Primary· 57.8%
#372832
Secondary· 18.2%
#552843
Secondary· 14.100000000000001%
#38142e
Secondary· 1.7%

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Scripts & Styles

23 Resources

20
Scripts
3
Styles
0
Async
2
Defer

Top Script Sources

reactivex.io(12)local(8)

Website Identity

reactivex.io

12 years old
Location detected: 🇺🇸 United Statesvia ip
Tucows Domains Inc.en-US

Social Profiles

X (Twitter)GitHub

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Last analyzed: 02 May 2026 at 03:24

Historical Analysis & Change Tracking