Bluesky Alt Text Checker
Write alt text for your image and check it for the mistakes that make alt text less useful to screen reader users.
- Processed locally
- No account required
- Image never uploaded
Your checklist will appear here
Write alt text on the left and check it.
Why alt text matters on Bluesky
Alt text is read aloud by screen readers in place of an image, so it is how blind and low-vision users experience your post's visual content. Bluesky's own image embed schema includes an alt field for exactly this purpose, and it has no fixed character limit in the protocol itself -- but very long alt text is harder for a screen reader user to sit through, so concise and specific beats exhaustive.
What this tool checks
- Length. Flags alt text that is likely too short to be useful, and alt text long enough that it may be better split or trimmed.
- Redundant openings. Phrases like "image of" or "photo of" are usually unnecessary -- screen readers already announce that an image is present.
- Generic or placeholder text. Catches alt text that is just a filename, or a generic word like "image" or "photo" with nothing describing what's actually shown.
- ALL CAPS. Some screen readers read capitalized text letter-by-letter, which can make alt text hard to follow.
- Empty alt text. Not flagged as an error -- an empty
altis the correct choice for a purely decorative image that adds no information.
How to write good alt text
Describe what's actually in the image and why it matters in context -- not every visual detail. For a screenshot, describe what it shows and any text that matters (a UI label, a chart's headline number). For a photo, describe the subject and action, not the color of every object. If the image contains text your post depends on (like a quote graphic), include that text in the alt text, since it will not otherwise reach someone using a screen reader.
Privacy first
If you choose an image, it is only read into your browser to show you a preview while you write -- it is never uploaded, and this tool makes no network request with your image or alt text. Closing or reloading the page discards everything.
More free tools
See all free SkyyCast tools. Before you post, check the image itself with the Bluesky Image Size Checker, and read our guide on how to add alt text on Bluesky.
Ready to schedule the post, too?
SkyyCast helps you plan, queue and schedule Bluesky content -- alt text included -- and see how each post performs. The Free plan includes 15 published posts a month.
See how it works