The "Image Alt Test" tool from TeckBlaze analyzes alt text on <img> tags in real time. You enter a URL above, we fetch the page exactly as Googlebot would, isolate the tested element, compare it to 2026 best practices, and tell you in plain words whether it passes, needs work, or is critical.
Why image alt test still matters in 2026
Images often account for 60% of a page's weight. Poorly optimized, they slow load times, degrade Core Web Vitals and break accessibility.
The newer reason: AI answer engines and link previews
AI agents don't see images — they read alt attributes. Without a written description, your visual is invisible to ChatGPT and invisible to Google Images.
Common mistakes worth checking
Missing alt text on content images.
JPG/PNG format where WebP/AVIF would save 50% weight.
No width/height attributes (triggers CLS).
Hero image loaded before useful HTML (LCP degraded).
Filenames like IMG_4582.jpg instead of descriptive names.
How do I fix it?
Fixing alt text on <img> tags usually takes minutes once you know where to look. Below: the code example, where to edit it based on your stack, the usual causes, and the best practices that keep the issue away.
Example
HTML
<img src="audit-dashboard.webp" alt="Tableau de bord d'audit SEO TeckBlaze">
Where to make the change
WordPress: via the theme (header.php / Yoast / Rank Math) or a dedicated SEO plugin.
Shopify: under Online Store → Preferences or in the theme's Liquid code.
Static HTML site: directly in the page's source file.
Next.js / React: via the framework's <head> metadata (Next Metadata API, react-helmet, etc.).
Other CMS: SEO panel in the admin, or edit the template.
Common causes and resolution
Theme or CMS template that does not handle alt text on <img> tags cleanly.
Recent site updates that overwrote a previous fix.
Domain or platform migration with configuration not carried over.
Misconfigured SEO plugin overwriting alt text on <img> tags defined elsewhere.
Best practices
Serve WebP by default, AVIF for capable browsers.
Always set width and height to avoid CLS.
Provide a descriptive alt (3–10 meaningful words).
Compress at max 80% quality.
Lazy-load everything not above the fold.
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