Alt Text Checker: Find Missing, Empty, and Suspicious Image Alt Text

Why alt text matters

Alt text (the alt attribute on an image) is the text alternative a screen reader reads aloud when it reaches an image. For someone who is blind or has low vision, alt text is often the only way to understand what an image conveys. When it is missing, the reader may announce nothing useful or fall back to reading the raw filename, which turns a meaningful photo into a string like IMG_4521.jpg. That is a real barrier, not a cosmetic detail.

Under the Web Content Accessibility Guidelines, Success Criterion 1.1.1 (Non-text Content, Level A) requires that non-text content have a text alternative that serves an equivalent purpose. Alt text is the primary way you meet that criterion for images. It is a Level A requirement, which means it is considered foundational rather than optional.

Good alt text also has secondary benefits. Search engines use it to understand image content, and it displays when an image fails to load. But the core reason to get it right is that real people rely on it. AccessGuard treats alt text as a first-class signal and reports exactly which images on a page are missing it or handling it poorly.

Good alt text vs bad alt text

Good alt text describes the content and function of an image in the context of the page, as briefly as possible while still conveying the same information a sighted user would get. It does not repeat what nearby text already says, and it does not stuff in keywords. A useful test: if you replaced the image with your alt text, would the sentence or section still make sense?

Avoid starting with phrases like "image of" or "photo of." Screen readers already announce that an element is an image, so those words are redundant noise. Also avoid vague filler like "graphic" or "picture," and never leave the filename as the description. There is no strict character limit, but aiming for a concise sentence (often around 125 characters) keeps things readable, and genuinely complex images like charts deserve a longer description nearby.

Here are quick examples. Bad: alt="IMG_2048.jpg" or alt="image of a chart." Better: alt="Chef slicing vegetables on a wooden cutting board." For data: bad is alt="a bar chart," better is alt="Bar chart showing accessibility issues dropping 40 percent after remediation." For a functional image like a logo that links home, describe the action: alt="VASTROX home."

• Describe content and function, not the fact that it is an image
• Skip "image of" and "photo of" prefixes
• Never leave the filename as the alt value
• Do not duplicate adjacent caption or body text
• Keep it concise; give complex charts a longer description nearby
• Write for the context the image appears in

Decorative images and the empty alt attribute

Not every image needs a description. Purely decorative images, such as a divider line, a background flourish, or an icon that sits next to text that already says the same thing, add nothing new for a screen reader user. For these, the correct approach is an explicitly empty alt attribute: alt="" (sometimes called null alt text).

The distinction matters. An empty alt="" tells assistive technology to skip the image entirely, which is exactly what you want for decoration. Omitting the alt attribute altogether is not the same thing. When alt is missing, some screen readers announce the filename or flag an unlabeled image, creating clutter and confusion. So decorative images need empty alt, not absent alt.

Deciding whether an image is decorative or informative is a judgment only the author can make, based on why the image is on the page. AccessGuard cannot read your intent, so it flags empty and missing alt as items for you to confirm rather than silently passing them. The rule of thumb: if the image carries meaning, describe it; if it is purely visual seasoning, give it alt="" so it is intentionally ignored.

When to describe and when to stay silent

Start by asking what job the image does on the page. Informative images (a product photo, a diagram, a screenshot that demonstrates a step) need alt text that conveys their meaning. Functional images that act as links or buttons need alt text that describes the action, such as "Search" for a magnifying glass icon that submits a form, not "magnifying glass."

Complex images like charts, graphs, and infographics need a short alt that names what the image is, plus a longer description available in the surrounding text or a linked detail. Do not try to cram an entire data table into a single alt attribute. Images of text should be avoided where possible, but when unavoidable, the alt must contain the same words shown in the image.

Stay silent, using alt="", when the image is decorative, redundant with adjacent text, or used only for layout. This is where good judgment beats blanket rules. AccessGuard surfaces every image and its current alt state so you can apply these decisions quickly instead of hunting through source code.

How AccessGuard finds missing and suspicious alt text

AccessGuard's free scanner crawls the page, inspects every img element and relevant role, and reports the alt situation for each one. It separates hard failures (images with no alt attribute at all) from items that need human review (empty alt on images that look informative, or alt values that appear low quality).

Beyond simply missing versus present, the scanner looks for suspicious patterns that usually signal a problem: alt text that matches a filename, values like "image," "photo," or "untitled," alt that duplicates a nearby heading or caption, and unusually long alt on images that should be simple. These heuristics catch the cases where an image technically has alt text but it is not actually useful to a screen reader user.

Each finding comes with plain developer fix guidance: the specific element, why it was flagged, and how to correct it, whether that means writing a real description or setting alt="" for decoration. You can run the free scanner on any URL, install the WordPress plugin to check content as you publish, and export PDF reports to share with your team. If you would rather hand the work off, VASTROX also offers web development, WordPress maintenance, and accessibility repair services to remediate the issues the scanner finds.

Accessibility scanning and legal readiness

Fixing alt text improves real usability and moves you toward WCAG conformance, and it is a strong signal of European Accessibility Act (EAA) readiness. Clear image descriptions are one of the most visible and frequently cited accessibility improvements, so they are a sensible place to start.

That said, AccessGuard provides accessibility scanning, WCAG issue detection, EAA readiness signals, and developer fix guidance. It is not legal advice and does not guarantee legal compliance. Automated tools, including ours, can reliably detect missing and structurally suspect alt text, but they cannot judge whether a description is accurate and meaningful for every image. That final judgment is human work.

Use AccessGuard to find the gaps fast, apply the guidance to fix them, and combine automated scanning with manual review for the images that require author judgment. For anything touching legal obligations, consult a qualified professional. Our goal is to make the technical path to better accessibility clear, measurable, and genuinely helpful.

Frequently asked questions

More accessibility checkers