Image Alt Text Checker
Alt text is the bridge between your images and both screen readers and search engines. Our checker parses every <img> tag in your HTML (or fetched from a URL) and flags the 5 most common problems: missing alt attributes, empty alt on informative images, generic labels like “image” or “IMG_4523.jpg”, keyword stuffing, and oversized alt descriptions. Each flagged image gets a severity badge, a plain-English explanation, and a context-specific fix recipe. The 0-100 score weights missing alts heavily (accessibility is non-negotiable) while giving credit for descriptive, concise alts. Runs entirely client-side unless you opt to fetch a URL.
Paste HTML above with <img> tags to check alt text.
Runs 100% in your browser. Nothing leaves your device.
Related glossary terms
Want a deeper dive? These glossary entries explain the concepts behind this tool.
How to use it
Paste HTML or fetch a URL
Switch to the ‘Paste HTML’ tab to drop in a code snippet with <img> tags, or switch to ‘Fetch a URL’ to analyze any public page. The URL fetcher uses the same secure server-side pipeline as our AI Overview Checker.
See your alt score + flagged images
In milliseconds, you get a 0-100 score (green 90+, amber 65-89, red <65) and a list of every <img> tag, color-coded by severity.
Click into any flagged image for the fix
Each ‘caution’ or ‘missing’ row expands to show the exact issue (missing attribute, empty alt, keyword stuffing, generic label, etc.) and a context-specific fix recipe with a copy-paste example.
Fix and re-check
Update your CMS or HTML, then re-paste or re-fetch to see the score climb. The checker is stateless — nothing is saved between runs.
Frequently Asked
Questions
Everything you need to know about image alt text, accessibility, and SEO in 2026.
Alt text (short for “alternative text”) is the text attribute you put inside an <img> tag, written as alt=“your description here”. It serves two purposes: (1) screen readers read it aloud so blind and low-vision users can understand what the image shows, and (2) search engines use it to understand the image’s content for ranking in Google Images and for contextual relevance. Per WebAIM’s 2024 survey of the top 1 million homepages, 31.3% of images have alt text issues — either missing, empty, or uninformative. W3C’s Web Content Accessibility Guidelines (WCAG 2.2, success criterion 1.1.1) require non-text content to have a text alternative.
Yes, but not the way most people think. Google has confirmed that alt text is used for image search ranking and for understanding page context, but it’s not a direct ranking factor for traditional web search. However, well-written alt text drives traffic from Google Images (which accounts for ~22% of all web searches per SparkToro 2024) and improves the page’s topical relevance for the surrounding text. Per Ahrefs’ 2025 study of 2.3M pages, pages with descriptive alt text on every image averaged 12% more organic traffic than pages with missing/empty alts — mostly driven by Google Images referral traffic.
Aim for 5-125 characters. The WebAIM and W3C consensus is that good alt text is “as long as necessary, as short as possible” — typically 1-2 sentences that convey the image’s purpose in context. Per Moz’s 2024 image SEO guide, the sweet spot is around 100-125 characters (10-15 words). Below 5 characters is almost always too vague (“dog”, “chart”); above 200 characters is usually too detailed and the description belongs in the surrounding text or an aria-describedby attribute instead.
Yes — but only for truly decorative images (dividers, ornamental icons, background graphics with no informational value). Use alt="" (empty string, not missing attribute) to signal to screen readers “skip this, it’s decoration”. W3C’s WCAG 2.2 decision tree is clear: if the image conveys information, give it real alt text; if removing the image would not change the page’s meaning, it’s decorative and gets alt="". Per WebAIM’s 2024 data, 8.4% of homepage images are decorative — mostly dividers and social icons duplicated as CSS background.
No — Google has explicitly penalized keyword-stuffed alt text since the 2007 Florida update era. Stuffing (“SEO SEO SEO best SEO”) helps zero and hurts accessibility badly. Modern ranking systems (per Google’s own image search documentation) reward alt text that accurately describes the image and ignore or downgrade alt text that reads as “written for machines”. Per a 2024 Semrush analysis of 500K pages, pages with stuffed alt text averaged 34% lower Google Images traffic than pages with descriptive alts, even after controlling for image count and domain authority.
Yes on both. The checker is completely free, no signup, no email gate, no per-scan limit. The HTML parser and alt analysis run entirely in your browser via JavaScript — nothing about your HTML is sent to our servers. If you use the ‘Fetch a URL’ feature, the URL is sent to our server-side fetcher (same secure pipeline as our AI Overview Checker, with SSRF defense and a 10/hour rate limit per IP), but the HTML is parsed and analyzed client-side. We don’t log URLs, don’t store HTML, and don’t train any AI on your inputs.
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