Accessibility

· 13 checks — Landmarks, headings, alt text, forms, and link quality rolled into one auditable list.

SCORE

GRADE

FIX

REVIEW

PASS

INFO

Checks

4 PASS 2 REVIEW 7 FIX

Landmark Structure

Action

No landmarks

FIX

No landmarks

No <main> landmark found

Screen reader users cannot quickly navigate to the primary content. Wrap your main content in <main>.

No <nav> landmark found

No banner (header) landmark

No contentinfo (footer) landmark

Skip navigation link is missing (WCAG 2.4.1)

Add a skip link as the first focusable element so keyboard users can bypass repeated navigation.

No landmarks detected

Screen reader users have no way to navigate by region.

Screen reader users cannot quickly navigate to the primary content. Wrap your main content in <main>.

Why this matters

Without a <main> landmark, screen-reader users can't skip past the navigation to the page content — every page starts with re-reading the menu.

Learn more ▾

The <main> element marks the page's primary content area. Assistive tech offers a 'jump to main' shortcut — but only if <main> exists. Without it, every page navigation forces re-reading the header. Wrap your primary content in a single <main>.

Source: WAI-ARIA / WCAG 2.4.1

Add a skip link as the first focusable element so keyboard users can bypass repeated navigation.

Why this matters

Without a skip-nav link, keyboard users tab through every nav item before reaching content — every page, every visit.

Learn more ▾

WCAG 2.4.1 (Bypass Blocks) requires a mechanism to skip past repeated content. The standard implementation is a 'Skip to main content' link that's the first focusable element, visually hidden until focused. Three lines of HTML + four of CSS.

Source: WCAG 2.1 SC 2.4.1

404 Error Page

Action

HTTP 404, bare page

FIX

HTTP 404, bare page

Correct 404 status code returned

Got: HTTP 404

Bare server default 404 page

The 404 page has no custom styling. Users hitting a broken link see a generic error with no way to navigate back. Add a custom 404 page with your site navigation and a search bar.

404 Page Quality Default 404 Page

Status Code HTTP 404 ✓Page Title 404 Not Found ✓Custom Styling ✗Navigation ✗Homepage Link ✗Search Form ✗

Favicon & Branding

Action

1 icon(s) detected

FIX

1 icon(s) detected

favicon.ico present at site root

No apple-touch-icon detected

iOS devices use this when users add your site to their home screen. Add <link rel='apple-touch-icon' sizes='180x180' href='/apple-touch-icon.png'>.

✓ favicon.ico Present

✗ PNG Icons Missing

✗ Apple Touch Missing

✗ SVG Favicon Missing

✗ Manifest Icons Missing

✗ Multiple Sizes Missing

Web Manifest

Action

Not found

FIX

Not found

No web manifest found

No manifest at standard paths (/manifest.json, /site.webmanifest). A manifest is optional but enables PWA features like home screen installation and standalone display.

No web manifest found.

Dark Mode Support

Action

No dark mode signals

FIX

No dark mode signals

No dark mode signals detected

Consider adding CSS with @media (prefers-color-scheme: dark) and <meta name='color-scheme' content='light dark'>.

Detection limited to meta tags and inline styles

External CSS files may contain prefers-color-scheme rules not visible to this scan.

Dark ModeNo Dark Mode Detected

color-scheme meta Not set ✗Dark theme-color Not set ✗CSS indicators Not detected ✗

Detection limited to meta tags and inline styles.

Print Stylesheet

Action

No print styles

FIX

No print styles

No print-specific styles detected

When users print this page, they get the screen layout including navigation and non-essential elements. Add @media print rules to hide navigation and optimize layout for paper.

Print Stylesheet No Print Styles

Print stylesheet Not found ✗Inline @media print Not detected ✗

Heading Hierarchy

7 headings, 1 skip(s)

REVIEW

7 headings, 1 skip(s)

Single H1 present

Heading level skipped: H1 → H3 (missing H2)

Skipping heading levels breaks the document outline. Screen readers may interpret missing levels as structural errors.

1 empty heading(s)

Empty headings appear in the document outline but provide no information.

H1 (empty)
H3 A Massively Spiffy Yet Delicately Unobtrusive Compression Library (Also Free, Not to Mention Unencumbered by Patents) skipped
H4 (Not Related to the Linux zlibc Compressing File-I/O Library)
H3 zlib Information
H3 CRC (Cyclic Redundancy Check) Bonus Information
H3 ZIP File Processing Bonus Software
H3 Related External Links

Skipping heading levels breaks the document outline. Screen readers may interpret missing levels as structural errors.

Why this matters

Skipping heading levels breaks the document outline — screen-reader users lose track of section nesting.

Learn more ▾

Screen reader users navigate by jumping between headings (H1 → H2 → H3). Skipping (H1 → H3) breaks the sense of hierarchy. Use sequential levels even if you don't like the default styling — restyle with CSS instead. WCAG 1.3.1 (Info and Relationships) treats this as an A failure.

Source: WCAG 2.1 SC 1.3.1 / W3C WAI

Empty headings appear in the document outline but provide no information.

Why this matters

Empty <hN> tags break the document outline — screen-reader users navigating by heading hit dead silence.

Source: WCAG 2.4.6

Lighthouse Accessibility Audits

Action

Score 74/100 — 5 failing, 11 passed

REVIEW

Accessibility

These checks highlight opportunities to improve the accessibility of your web app. Automatic detection can only detect a subset of issues and does not guarantee the accessibility of your web app, so manual testing is also encouraged.

Tables and lists

When definition lists are not properly marked up, screen readers may produce confusing or inaccurate output. Learn how to structure definition lists correctly.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
Canonical URL: https://zlib.net/ (US) `body > dl`
zlib source code, version 1.3.2, tar.gz format (1468K, SHA-256 hash bb329a0a2c… `body > dl`
US (zlib.net) (GPG signature) `body > dl > dd > dl`
US (zlib.net) (GPG signature) `body > dl > dd > dl`
US (zlib.net) (GPG signature) `body > dl > dd > dl`
https://zlib.net/current/zlib.tar.gz `body > dl`
zlib Frequently Asked Questions Zlib-announce mailing list New versions of zl… `body > dl`
New versions of zlib are announced on this list. `body > dl > dd > dl`
Please do not send questions or comments about zlib to this mailing list. Send … `body > dl > dd > dl`
Ross Williams' classic "A Painless Guide to CRC Error Detection Algorithms" C… `body > dl`
Code to read a zip file as a stream and extract its contents. sunzip.c will re… `body > dl`
zlib for Linux, both shared and static plus headers (RPM format, many architec… `body > dl`
(unsupported VB5 binary also available) `body > dl > dd > dl`
(includes compiled object files and corresponding C++ Builder 5 project files) `body > dl > dd > dl`
(not tested by us, but looks like a good alternative to java.util.zip) `body > dl > dd > dl`
(see also Info-ZIP's UnZip, which optionally can be compiled with zlib) `body > dl > dd > dl`
(not tested by us, but looks like a good alternative if you need more speed and… `body > dl > dd > dl`
(not tested by us, but looks like an even better alternative if you need more s… `body > dl > dd > dl`
(not tested by us, but appears to be a better alternative to zlib in both dimen… `body > dl > dd > dl`
(not tested by us, but looks like a good alternative if you need more compressi… `body > dl > dd > dl`

These are opportunities to improve the experience of reading tabular or list data using assistive technology, like a screen reader.

Navigation

Properly ordered headings that do not skip levels convey the semantic structure of the page, making it easier to navigate and understand when using assistive technologies. Learn more about heading order.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
A Massively Spiffy Yet Delicately Unobtrusive Compression Library (Also Free, N… `body > h3`

These are opportunities to improve keyboard navigation in your application.

Internationalization and localization

If a page doesn't specify a `lang` attribute, a screen reader assumes that the page is in the default language that the user chose when setting up the screen reader. If the page isn't actually in the default language, then the screen reader might not announce the page's text correctly. Learn more about the `lang` attribute.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
html `html`

These are opportunities to improve the interpretation of your content by users in different locales.

Best practices

Touch targets with sufficient size and spacing help users who may have difficulty targeting small controls to activate the targets. Learn more about touch targets.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
zlib Frequently Asked Questions `body > dl > dd > a`
Zlib-announce mailing list `body > dl > dd > a`
zlib Manual `body > dl > dd > a`
zlib Usage Example `body > dl > dd > a`
zlib Technical Details `body > dl > dd > a`
RFC 1950 ZLIB Compressed Data Format Specification version 3.3 `dd > ul > li > a`
RFC 1951 DEFLATE Compressed Data Format Specification version 1.3 `dd > ul > li > a`
RFC 1952 GZIP file format specification version 4.3 `dd > ul > li > a`
zlib's Deflate Algorithm `body > dl > dd > a`
zlib's deflate flush modes `body > dl > dd > a`
zlib License `body > dl > dd > a`
All released versions of zlib `body > dl > dd > a`
zlib on github `body > dl > dd > a`
Ross Williams' classic "A Painless Guide to CRC Error Detection Algorithms" `body > dl > dd > a`
zlib for Palm Pilot `body > dl > dd > a`
zlib for Newton OS `body > dl > dd > a`
zlib for Windows CE `body > dl > dd > a`
zlib for .NET in C# `body > dl > dd > a`
zlib DLL wrapper for .NET in C# `body > dl > dd > a`
Zip for .NET `body > dl > dd > a`
zlib Haskell interface `body > dl > dd > a`
zlib reimplementation in pure Java `body > dl > dd > a`
zlib technical issues, including spec errors `body > dl > dd > a`
Zip Files: History, Explanation and Implementation `body > dl > dd > a`
zlib information in Japanese `body > dl > dd > a`
zlib information in Russian `body > dl > dd > a`
Info-ZIP Home Page `body > dl > dd > a`
gzip Home Page `body > dl > dd > a`
pigz (parallel gzip) Home Page `body > dl > dd > a`
DataCompression.info `body > dl > dd > a`

One main landmark helps screen reader users navigate a web page. Learn more about landmarks.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
html `html`

These items highlight common accessibility best practices.

○Interactive controls are keyboard focusable

○Interactive elements indicate their purpose and state

○The page has a logical tab order

○Visual order on the page follows DOM order

○User focus is not accidentally trapped in a region

○The user's focus is directed to new content added to the page

○HTML5 landmark elements are used to improve navigation

○Offscreen content is hidden from assistive technology

○Custom controls have associated labels

○Custom controls have ARIA roles

●`[aria-hidden="true"]` is not present on the document `<body>`

●Image elements have `[alt]` attributes

●Background and foreground colors have a sufficient contrast ratio

●Definition list items are wrapped in `<dl>` elements

●Document has a `<title>` element

●Links are distinguishable without relying on color.

●Links have a discernible name

●Lists contain only `<li>` elements and script supporting elements (`<script>` and `<template>`).

●List items (`<li>`) are contained within `<ul>`, `<ol>` or `<menu>` parent elements

●Cells in a `<table>` element that use the `[headers]` attribute refer to table cells within the same table.

●Identical links have the same purpose.

○`[accesskey]` values are unique

○`[aria-*]` attributes match their roles

○`button`, `link`, and `menuitem` elements have accessible names

○ARIA attributes are used as specified for the element's role

○Deprecated ARIA roles were not used

○Elements with `role="dialog"` or `role="alertdialog"` have accessible names.

○`[aria-hidden="true"]` elements do not contain focusable descendents

○ARIA input fields have accessible names

○ARIA `meter` elements have accessible names

○ARIA `progressbar` elements have accessible names

○Elements use only permitted ARIA attributes

○`[role]`s have all required `[aria-*]` attributes

○Elements with an ARIA `[role]` that require children to contain a specific `[role]` have all required children.

○`[role]`s are contained by their required parent element

○`[role]` values are valid

○Elements with the `role=text` attribute do not have focusable descendents.

○ARIA toggle fields have accessible names

○ARIA `tooltip` elements have accessible names

○ARIA `treeitem` elements have accessible names

○`[aria-*]` attributes have valid values

○`[aria-*]` attributes are valid and not misspelled

○Buttons have an accessible name

○The page contains a heading, skip link, or landmark region

○ARIA IDs are unique

○No form fields have multiple labels

○`<frame>` or `<iframe>` elements have a title

○`<html>` element has a valid value for its `[lang]` attribute

○`<html>` element has an `[xml:lang]` attribute with the same base language as the `[lang]` attribute.

○Input buttons have discernible text.

○`<input type="image">` elements have `[alt]` text

○Form elements have associated labels

○The document does not use `<meta http-equiv="refresh">`

○`[user-scalable="no"]` is not used in the `<meta name="viewport">` element and the `[maximum-scale]` attribute is not less than 5.

○`<object>` elements have alternate text

○Select elements have associated label elements.

○Skip links are focusable.

○No element has a `[tabindex]` value greater than 0

○`<th>` elements and elements with `[role="columnheader"/"rowheader"]` have data cells they describe.

○`[lang]` attributes have a valid value

○`<video>` elements contain a `<track>` element with `[kind="captions"]`

○Tables have different content in the summary attribute and `<caption>`.

○All heading elements contain content.

○Uses ARIA roles only on compatible elements

○Image elements do not have `[alt]` attributes that are redundant text.

○Elements with visible text labels have matching accessible names.

○Tables use `<caption>` instead of cells with the `[colspan]` attribute to indicate a caption.

○`<td>` elements in a large `<table>` have one or more table headers.

Alt Text Quality

67 of 73 images have issues

PASS

67 of 73 images have issues

67 image(s) with generic alt text

6 image(s) with good alt text

73 images 6 good alt text 67 generic

Issue	Count
generic	67 image(s)

A+

Form Accessibility

No form controls

PASS

No form controls

No form controls on this page

No form controls found.

A+

Link & Button Quality

109 links, 0 buttons — all OK

PASS

109 links, 0 buttons — all OK

109 link(s) with descriptive text

109 links

0 empty

0 generic text

0 new tab

0 empty buttons

All links and buttons have descriptive accessible text.

109 links and buttons have descriptive text

A+

Color Contrast (Screenshot)

20 text elements analyzed, 0 fail WCAG AA

PASS

Analyzes text contrast against the actual rendered page, including background images, gradients, and overlays that CSS-based tools cannot detect.

20 pass

Show all checked elements (20)

Element	Ratio	Required	FG	BG	Result
h3 A Massively Spiffy Y…	21.00:1	3.0:1	#000000	#FFFFFF	Pass
h3 (Also Free, Not to M…	21.00:1	3.0:1	#000000	#FFFFFF	Pass
h3 zlib Information	21.00:1	3.0:1	#000000	#FFFFFF	Pass
h3 CRC (Cyclic Redundan…	21.00:1	3.0:1	#000000	#FFFFFF	Pass
h3 ZIP File Processing …	21.00:1	3.0:1	#000000	#FFFFFF	Pass
h3 Related External Lin…	21.00:1	3.0:1	#000000	#FFFFFF	Pass
title zlib Home Site	21.00:1	4.5:1	#000000	#FFFFFF	Pass
i Not	21.00:1	4.5:1	#000000	#FFFFFF	Pass
h4 Related to the Linux…	21.00:1	3.0:1	#000000	#FFFFFF	Pass
p Welcome to the	21.00:1	4.5:1	#000000	#FFFFFF	Pass
b zlib	21.00:1	3.0:1	#000000	#FFFFFF	Pass
p home page, web pages…	21.00:1	4.5:1	#000000	#FFFFFF	Pass
a Mark Adler	21.00:1	4.5:1	#000000	#FFFFFF	Pass
p . If this page seems…	21.00:1	4.5:1	#000000	#FFFFFF	Pass
a PNG Home Page	21.00:1	4.5:1	#000000	#FFFFFF	Pass
p , rest assured that …	21.00:1	4.5:1	#000000	#FFFFFF	Pass
i completely	21.00:1	4.5:1	#000000	#FFFFFF	Pass
p coincidental. No, r…	21.00:1	4.5:1	#000000	#FFFFFF	Pass
b zlib	21.00:1	3.0:1	#000000	#FFFFFF	Pass
p was written by	21.00:1	4.5:1	#000000	#FFFFFF	Pass

Methodology: The top 20 text elements by font size were checked. Background color was sampled from the desktop screenshot using a 5-point pattern. WCAG 2.1 AA requires 4.5:1 for normal text and 3:1 for large text.

All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.