Paste any HTML snippet or full page source containing <img> tags.
Try a sample:
Paste HTML and run the check
All <img> tags will be analyzed for alt text quality// scan html for missing or weak image alt attributes
Check HTML for missing, empty, or poor-quality alt text on images. Improve accessibility and SEO by finding every image that needs a better description.
Paste any HTML snippet or full page source containing <img> tags.
Paste HTML and run the check
All <img> tags will be analyzed for alt text qualityCopy any HTML containing <img> tags — a snippet, a page section, or an entire source file.
Click "Check Alt Text" or press Ctrl+Enter. All images are scanned instantly.
Review each flagged image, understand the problem type, and update your HTML accordingly.
The Alt Text Checker scans your HTML and flags every <img> tag with missing, empty, generic, or low-quality alt attributes. Good alt text is critical for screen reader users and helps search engines understand your images.
Alt text (alternative text) is an HTML attribute added to <img> tags that describes the visual content of an image. It is read aloud by screen readers for visually impaired users, displayed when an image fails to load, and indexed by search engines to understand image content — all of which makes it essential for both accessibility and SEO.
No. An empty alt="" is correct and intentional for purely decorative images — icons used as visual flair, spacer images, or backgrounds that convey no meaningful information. This checker flags only images that completely lack the attribute, not those with deliberate empty alt values.
Generic alt text includes values like image, photo, picture, icon, placeholder, undefined, or null. These tell screen reader users nothing useful about what the image shows, and search engines gain no SEO value from them.
Screen readers automatically announce that an element is an image before reading the alt text. Starting your alt with "image of", "photo of", or "picture of" causes the user to hear "image: image of a cat" — redundant and annoying. Simply describe what is shown: "orange tabby cat sleeping on a chair".
Aim for under 150 characters — concise but descriptive. A useful rule: write what you would say if describing the image to someone on the phone. For complex images like charts or infographics, provide a short alt and a longer explanation in a nearby <figcaption> or paragraph. This tool flags alt text over 150 characters as a warning.
Yes, parsing is done server-side using PHP's DOMDocument — no third-party services are involved and no data is stored. Your HTML is processed only for the duration of the check request and is never logged or retained.
Currently the tool requires you to paste HTML source directly. To check a live URL, open the page in your browser, right-click and choose "View Page Source" (Ctrl+U), select all, copy, and paste into the input box.
The score reflects only the alt text quality of the images found in the pasted HTML. Full WCAG compliance covers many other criteria — color contrast, keyboard navigation, ARIA roles, focus management, and more. Use this tool as one part of a broader accessibility review.
An alt text checker is a tool that parses HTML and inspects every <img> element for the presence and quality of its alt attribute. The alt attribute — short for alternative text — is one of the most fundamental accessibility requirements on the web, yet it remains one of the most frequently neglected. Studies from the WebAIM Million report consistently find that missing or meaningless alt text is among the top five accessibility errors found on homepage audits across the web.
This tool goes beyond simply detecting a missing attribute. It categorizes issues into actionable types: missing alt attributes, generic placeholder values, filenames used as descriptions, redundant phrasing, and descriptions that are either too short to be meaningful or too long to be practical. Each finding includes a clear explanation and a recommended fix, making it useful not just for developers but also for content editors, QA teams, and SEO specialists.
Approximately 253 million people worldwide live with visual impairment according to the World Health Organization. Many of these users rely on screen readers — software that reads web page content aloud — to navigate the internet. When a screen reader encounters an <img> tag, it reads the alt attribute out loud. If the attribute is missing, the screen reader may instead read out the filename (e.g., "DSC00123.jpg") or skip the image entirely, leaving the user with no context about what they are missing.
Well-written alt text makes images understandable without seeing them. It creates an equivalent experience for blind users, low-vision users, and even users in situations where images fail to load due to slow connections or blocked content. Under the Web Content Accessibility Guidelines (WCAG 2.1), Success Criterion 1.1.1 requires that all non-decorative images have a text alternative — making meaningful alt text a legal requirement in many jurisdictions, not just a best practice.
Search engines cannot see images the way humans do. Google's crawlers read alt text to understand image content and determine relevance. High-quality alt text helps your images appear in Google Image Search, contributes to the overall topical relevance of your page, and is a known on-page SEO signal. Pages with properly described images tend to rank better for related queries, particularly in content-heavy niches like e-commerce, news, and editorial publishing.
The SEO and accessibility goals for alt text are nearly identical: both demand specific, accurate, human-readable descriptions. Generic values like "image", "photo", or a raw filename benefit neither Google nor a screen reader user. A description like "artisan sourdough loaf with scored crust on a wooden board" helps both a visually impaired user and Google Images indexing far more than "bread.jpg".
Missing alt attribute entirely. The most critical error. Every meaningful image must have an alt attribute. If the image is purely decorative (a background texture, a visual divider), use alt="" to explicitly mark it as presentational. If it conveys information, write a description.
Using the filename as alt text. CMS platforms sometimes auto-populate alt fields with the filename when images are uploaded. The result is alt values like "IMG_4892.jpg" or "hero-banner-v3-final.png". These are meaningless to screen reader users and provide no SEO value. Always replace auto-generated filenames with a real description.
Generic or placeholder values. Alt text that says "image", "photo", "icon", "placeholder", or "undefined" is worse than no description in some ways — it signals to the screen reader that a description was attempted but failed. These values often appear in templates and CMS themes where placeholder alt text was never updated before content went live.
Redundant phrasing. Starting alt text with "image of", "photo of", or "picture showing" is redundant because screen readers already announce the element type. "Image: image of a red car" becomes an annoying repetition. Simply write "red sports car parked outside a showroom" and let the screen reader handle the announcement.
Alt text that is too short. A one or two character alt like "X" or "." provides no useful information. Even for small icons, a brief label such as "close" or "external link" is far better than an arbitrary character.
Alt text that is too long. Very long alt text (over 150 characters) can overwhelm screen reader users who need to listen to the entire string before the page moves on. For complex images like infographics, charts, or diagrams, the best practice is a short alt with a longer plain-text description in an adjacent <figcaption> or a linked long description.
Good alt text is specific, concise, and contextual. The same image might have different appropriate alt text depending on its purpose on the page. A photo of a chef cooking on a restaurant homepage might warrant "Executive chef plating a dish in an open kitchen", while the same image in a recipe article could appropriately be "Chef slicing garlic for a pasta dish".
Here are practical rules to follow:
alt="" (empty, not omitted) for decorative images so screen readers skip them.The Alt Text Checker is particularly useful during several common workflows. Before launching a new website or page, paste the full page HTML to catch any missing or weak alt text before it reaches real users. After importing content from a CMS, blog platform, or design tool, run the output HTML through the checker to catch auto-generated filenames or template placeholder values. During an accessibility audit, use this tool alongside color contrast checkers, ARIA validators, and keyboard navigation tests to build a comprehensive picture of your page's accessibility health.
Email developers will also find it useful: HTML emails frequently contain images with missing alt text, which is especially problematic since many email clients block images by default, meaning alt text is often the only content a recipient sees until they click to download images.
The tool generates an accessibility score based on the percentage of images that pass all alt text checks. A score of 100% means every image either has valid alt text or has been explicitly marked decorative with alt="". A lower score indicates the proportion of images with actionable problems. This score is a useful snapshot metric for tracking improvements over time or comparing before and after a content update, but it is not a substitute for manual review or a full WCAG audit.