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About this tool
Draft and score alt text for social images against platform character limits and the 125-character screen reader guideline.
Social Alt Text Writer scores a draft image description against the platform's own field limit and the long-standing 125-character screen reader guideline, then names each thing that would make it awkward to listen to. It flags redundant openers like "image of", leftover file names, hashtags, all-caps runs, emoji pile-ups and keyword repetition, and it can assemble a first draft from the subject, the action, the setting and any words printed in the picture. WCAG 2.2 success criterion 1.1.1 requires a text alternative for non-text content; this tool helps you write one that is actually useful.
Open Social Alt Text Writer on AltFTool — it loads instantly in your browser.
Choose Where the image will be posted and paste your draft into Your alt text — LinkedIn caps at 120 characters and X at 1,000.
Read the Alt text score out of 100 with the flags for "image of" openers, leftover file names, hashtags and emoji; the score updates as you type.
Press Copy alt text, or fill Main subject, What they are doing and Where it happens to have a first sentence assembled for you.
Checks against the published field limit where one exists and the 125-character guideline where it does not.
Every flag says what is wrong and what to change, rather than giving a bare score.
Builds a first sentence from subject, action, setting and on-image text so you are never starting from a blank field.
Keep it under about 125 characters. That figure is a working guideline rather than a WCAG rule — it comes from screen readers that historically stopped announcing an alt attribute around that length. If the image genuinely needs more explanation, put the detail in a visible caption or a long description and keep the alt attribute short.
No. Screen readers already announce that the element is an image, so "image of a woman cycling" is heard as "image, image of a woman cycling". Lead with the subject instead. The one exception is when the medium matters — "Oil painting of..." or "Pencil sketch of..." tells the listener something real.
X accepts up to 1,000 characters in its image description field and LinkedIn caps alt text at 120 characters. Instagram and Facebook do not publish a figure for custom alt text, so the 125-character guideline is the safer target on both.
No — a purely decorative image should carry an empty alt attribute (alt="") so screen readers skip it entirely. Describing a background flourish or a divider line just adds noise. On social platforms, leaving the field blank on a decorative graphic has the same effect.