Why is a missing alt attribute worse than an empty one?

When the alt attribute is entirely absent, screen readers commonly fall back to announcing the image's filename ("IMG_4821.jpg") since they have nothing else to work with, which is actively unhelpful. An empty alt (alt="") is an explicit, valid signal that the image is decorative and should be skipped - the two cases look similar in a browser but mean opposite things to assistive technology.

So is alt="" always fine?

Only when the image is genuinely decorative and adds no information a reader would need - a divider graphic, a background flourish, an icon next to text that already says the same thing. If the image conveys information (a product photo, a chart, a screenshot, a logo used as a link), an empty alt hides that information from screen reader users and from image search, so this tool flags empty alt attributes for a manual check rather than treating them as automatically correct.

Does alt text actually help SEO, or is it purely an accessibility feature?

Both. Google has stated alt text helps it understand image content for Google Images ranking and for understanding the page overall, in addition to being read aloud by screen readers - the two goals reinforce each other, and writing alt text as a genuine, specific description serves both audiences well.

What should good alt text actually say?

A concise, specific description of the image's content or function as it relates to the surrounding page - "Red trail running shoe, side profile" rather than "image" or a keyword-stuffed string like "running shoes best running shoes buy running shoes", which reads as spam to both search engines and screen reader users.

Image Alt Tag Checker - Find Missing & Empty Alt Attributes

Overview

Introduction

Alt text sits at the intersection of accessibility and SEO: it's read aloud by screen readers when an image can't be seen, shown as fallback text when an image fails to load, and used by search engines to understand what an image depicts. A missing or lazily-empty alt attribute quietly fails all three at once, and it's easy to miss because the page looks completely normal to a sighted visitor with working images.

This tool fetches a page (or reads pasted HTML) and categorizes every <img> tag by its alt-attribute status, distinguishing the two very different cases that look identical in a browser: attribute missing entirely versus attribute present but deliberately empty.

What Is Image Alt Tag Checker?

An image accessibility auditor that parses every <img> element on a page and reports, for each one, whether its alt attribute is absent, present-but-empty, or present with text - plus a summary count across the whole page.

It works two ways: fetching a URL directly from your browser when the target allows cross-origin requests, or reading HTML you paste in yourself, which works on any page regardless of CORS.

How Image Alt Tag Checker Works

The HTML is parsed with the browser's own DOMParser, and every <img> tag is inspected for the literal presence of an alt attribute (not just whether its value happens to be an empty string) - this distinction matters because HTML treats a missing attribute and an attribute set to an empty string differently, even though most browsers render them identically.

Each image is then bucketed into missing, empty, or present, with its (truncated) src shown alongside so you can locate it in the page, and a running summary count is shown above the full list.

When To Use Image Alt Tag Checker

While auditing a page or whole site section for accessibility gaps, since missing alt text is one of the most common and most consequential WCAG failures found in automated audits.

Right after a CMS migration or bulk image upload, since import scripts and page builders frequently drop the alt field or leave it blank by default unless a workflow explicitly forces authors to fill it in.

Often used alongside Heading Structure Analyzer and Meta Tag Checker.

Features

Advantages

Distinguishes a genuinely missing alt attribute from a deliberately empty one, a distinction most quick visual checks miss entirely.
Shows a running summary count alongside the full per-image list, so a large page's overall alt-text health is visible at a glance before scrolling through every row.
Works on any page via the paste-source fallback, not just pages that happen to allow cross-origin fetches.

Limitations

Only reads the static HTML; images injected client-side after page load by JavaScript (common in single-page apps and infinite-scroll galleries) won't appear unless they're already in the fetched or pasted source.
Can't judge whether present alt text is actually a good, accurate description versus a lazy placeholder like "image" or "photo" - that judgment call still needs a human reading each one.

Examples

A page with mixed alt-text quality

Input

<img src="/hero.jpg">
<img src="/divider.png" alt="">
<img src="/shoe-red.jpg" alt="Red trail running shoe, side profile">

Output

3 images: 1 missing, 1 empty (fine only if decorative), 1 with alt text

The hero image has no alt attribute at all (a real gap), the divider has an explicit empty alt (correct if it's purely decorative), and the product photo has descriptive text (good).

Best Practices & Notes

Best Practices

Write alt text that describes what the image shows or does, not what you want it to rank for - specific and accurate beats keyword-heavy every time.
Use an explicit empty alt (alt="") for genuinely decorative images rather than leaving the attribute off entirely, so assistive technology can confidently skip it instead of guessing.

Developer Notes

Alt status is determined by attribute presence via hasAttribute, not by checking truthiness of the value, so alt="" (present, empty string) is correctly distinguished from no alt attribute at all (missing) even though both produce the same visual result in a browser.

Image Alt Tag Checker Use Cases

Running a pre-publish accessibility check on a new landing page's images
Auditing an e-commerce product listing template for missing alt text across hundreds of product photos
Verifying a CMS bulk-import didn't silently drop alt text that existed in the original source

Common Mistakes

Leaving alt text off entirely instead of setting an explicit empty alt="" for decorative images, forcing screen readers to fall back to announcing the filename.
Filling every image's alt text with the same keyword phrase site-wide instead of describing what that specific image actually shows.

Tips

If an image is also a link (e.g. a logo wrapped in <a>), its alt text should describe the link's destination or action, not just the image content, since that's what a screen reader user will hear as the link's label.

Image Alt Tag Checker