swi-prolog.org

https://swi-prolog.org· First analyzed 29 Apr 2026· Updated 29 Apr 2026

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swi-prolog.org

Mobile

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Hosting Provider

IONOS (1&1)

ionos.com

IP Address

194.164.198.54

Site Location

🇩🇪 Germanyvia ip

Server Location

🇩🇪 Berlin, Germany

ASN

AS8560

Organization

IONOS SE

Server

Nginx

CDN

Fastly

Nameservers

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

Performance

Core Web Vitals

Weight

First Contentful Paint

894 ms10%

Speed Index

1.2 s10%

Largest Contentful Paint

—25%

Total Blocking Time

0.0 ms30%

Cumulative Layout Shift

0.00025%

423 KB

17 requests

0–49

50–89

90–100

Architecture Stack

Monolithic

⚙️ SSR

Infrastructure

Hosting

IONOS (1&1)

CDN

Fastly

Technology Stack

3 Technologies Detected

Libraries

jQueryv3.6.0

jQuery UI

Web Servers

Nginxv1.24.0

SEO Analysis

D40/100

Meta Tags4/15

Content9/12

Headings0/8

Technical6/21

E-E-A-T0/7

Images4/7

Links5/5

URL5/5

Social0/5

Freshness0/4

Mobile4/4

Indexability3/3

swi-prolog.orgswi-prolog.org

SWI-Prolog

No description available for this page.

Title Length10 chars

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

Description Length0 chars

Recommended: 120-160 chars

Issues (3)

• Missing meta description — important for click-through rates in SERPs
• Missing H1 tag — every page should have exactly one H1
• Missing viewport meta tag — page may not be mobile-friendly (Google uses mobile-first indexing)

10 issues found

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Local SEO

Local Search Readiness

0/100

Poor

15 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

F26/100

Bot Access

20/25

Machine Read.

2/25

Schema Data

0/25

Citation

4/25

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:14%

Words:214

Token eff.:Too Short

Structured Data

No Schema

Citation Readiness

Opening Summary

Descriptive Headings

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.

63/100

Passed

Critical

Warnings

Images & Alt Text

20/20

Checks if images have descriptive alt text for screen readers and visually impaired users.

Semantic Structure

3/20

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

6/15

Checks correct use of WAI-ARIA attributes (roles, states, properties) for assistive technologies.

4 recommendations

•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.

64/100

43 mg

CO₂e / view

422.7 KB

Page Weight

90%

Cleaner Than

New Visitor

49 mg

Returning (cached)

24 mg

Annual (10K/mo)

5.1 kg

Emission Segments

Data Center

2 mg

Network

13 mg

Device

28 mg

Resource Breakdown

JavaScript

338.7 KB

Images

19.4 KB

CSS

60.1 KB

HTML

4.0 KB

Other

541 B

Green Hosting Verified

IONOS SE

GWF Verified

3 recommendations

•Carbon footprint recommendation preview...

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Security Score

56%Poor

Interactive

HTTPS

No WAF

227d

Certificate Details

Type

Domain Validated (DV)

Certificate Authority

GlobalSign nv-sa

Key Algorithm

RSA (2048 bit)

Signature

SHA-256 with RSA

TLS Version

TLSv1.2

HTTP Protocol

HTTP/2

Valid From

10.11.2025

Valid Until

12.12.2026

OCSP Stapling

Enabled

Subject Alternative Names (1)

www.swi-prolog.org

SHA-256 Fingerprint

E4:4B:3A:1C:2C:DE:06:CB:A8:0E:A0:93:29:83:7C:D8:34:04:3F:2D...

Top Recommendations

Security recommendation preview

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HTTP Headers

Developer Console

accept-ranges

bytes

age

3294

content-encoding

📦 Gzip(gzip)

content-length

3747

content-security-policy

frame-ancestors 'none'

content-type

text/html; charset=UTF-8

Good Warning Issue

Email Infrastructure

Custom Mail Server

Score

SPF

DKIM

DMARC

DMARC Policy

None (Monitor Only)

MX Records (1)

mx.transip.email

Domain Information

swi-prolog.org

Domain Age

24y 4m

Created

17.12.2001

Expires

17.12.2026

Last Updated

31.01.2026

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.

37/100

Not 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.

4 recommendations

•Mobile compatibility recommendation preview...

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Typography & Readability

sans

WCAG Partial

58/100

Readability

/30

21/30

16px · LH --

Hierarchy

/20

10/20

WCAG

/25

14/25

1:1 min contrast

Performance

/25

13/25

2 fonts · 2 req

Heading Font

sans

Body Font

sans

Sans16px

Contrast Ratio

1:1

16 issues

Reading Comfort

Single Family

left aligned

16px

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

⚠️ Hard to read: Flesch score 44/100. Simplify sentences for wider reach.

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

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

⚠️ Missing font-display: swap — users may see invisible text while fonts load (FOIT).

Buy on MyFontsFlesch 44

Color Palette

7 unique colors

5.48:1 AA Light

#ffffff

Background· 18.2%

#636a71

Other· 6.8%

#ebebe3

Primary· 61.00000000000001%

#c8a989

Secondary· 5.4%

#344d68

Secondary· 3.3%

#988068

Secondary· 2.6%

Business & Marketing Stack

1 Tools Detected

Growing

Behavior Analytics

Google AnalyticsFree

User behavior and product analytics

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Scripts & Styles

9 Resources

Scripts

Styles

Async

Defer

Top Script Sources

local(3)buttons.github.io(1)

Website Identity

swi-prolog.org

24 years old

Location detected: 🇩🇪 Germanyvia ip

Key-Systems GmbH

Social Profiles

GitHub

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Last analyzed: 29 Apr 2026 at 15:43

Historical Analysis & Change Tracking