Generate a starting-point alt text description for any image entirely in your browser — a rule-based algorithm reads the filename, dimensions, and dominant colors, drafts a description, and lets you refine it by hand. No AI or upload required.
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Strong alt text is specific, concise, and contextual — it describes what a sighted user would actually notice about the image that's relevant to the surrounding content, not an exhaustive inventory of every visual detail. 'Red high-top sneakers on a white background' serves a product page well; 'A pair of shoes' is too vague to be useful, and a paragraph-length description of the stitching, laces, and lighting is usually more detail than the context calls for. The right amount of detail depends entirely on why the image is on the page — a product photo, an informative chart, and a decorative header background all warrant very different treatment.
Beyond feeding this tool's subject-guessing logic, descriptive filenames (golden-retriever-beach-run.jpg rather than IMG_4821.jpg) are themselves a minor, secondary SEO signal — Google Images has confirmed it considers filenames as one small contextual clue about an image's content, alongside alt text, surrounding page text, and captions. Renaming image files descriptively before uploading them, in addition to writing good alt text, is a low-effort habit that compounds across a site with hundreds or thousands of images.
These three are often confused but serve distinct purposes: alt text is read by screen readers and displayed if the image fails to load, and should describe the image's content and function. Title text (the title attribute) shows as a hover tooltip in most browsers and is not reliably read by screen readers at all — it's best used sparingly, for supplementary context rather than as a substitute for alt text. A visible caption sits below or beside an image as regular page content, readable and visible to everyone, and can go into more narrative or editorial detail than alt text should. A well-built image often has different, non-redundant content in each of the three.
The most frequent mistakes are: leaving alt text empty on a genuinely meaningful image (making it invisible to screen reader users and search engines alike); stuffing alt text with unrelated keywords purely for SEO, which both violates search engine guidelines and produces a nonsensical experience for screen reader users; using a generic, unhelpful description like 'image' or 'photo1'; and writing alt text so long and detailed that it becomes tedious for a screen reader user to sit through before reaching the next piece of content. Good alt text threads the needle between too little and too much, staying focused on what's actually relevant.
Different kinds of images call for different alt text strategies: a product photo should mention the product, its key visible attributes, and variant details (color, angle) if relevant. An infographic or chart needs alt text that either summarizes its key takeaway concisely or, for complex data, a short alt text plus a fuller text-based description elsewhere on the page (since alt text alone often isn't enough to convey a detailed chart's full information). A logo used as a homepage link typically just needs the company name. A purely decorative background pattern needs no descriptive alt text at all — just an empty alt="" attribute so screen readers skip it entirely.
Alt Text Generator pairs naturally with these SEO and image tools for accessible, well-optimized content.