By Chris Greenacre in Tophhie Social — 25 Nov 2025

Measuring Accessibility in Bluesky Posts: Introducing the Accessibility Score

We're introducing a new scoring system for Tophhie Social users and the accessibility of their Bluesky posts.

Accessibility isn’t just a checkbox - it’s a commitment to making content usable for everyone. On platforms like Bluesky, where visual content is common, ensuring that images include descriptive alt text is critical for users relying on screen readers or assistive technologies.

To help quantify this, I’ve introduced an Accessibility Score for Bluesky posts hosted on Tophhie Social. This score provides a simple, transparent way to evaluate how well a user’s posts meet accessibility best practices.

What is the Accessibility Score?

The Accessibility Score is a metric (0–100) that reflects how effectively a user includes alt text for images in their posts. It considers two key factors:

Image-Level Coverage (80% weight)
The percentage of all images across posts that include meaningful alt text.
Post-Level Completeness (20% weight)
The percentage of image-containing posts where every image has alt text.

This dual approach rewards both breadth (most images have alt text) and completeness (entire posts are accessible).

How is it calculated?

For a given user:

Total Posts: All Bluesky posts retrieved from Tophhie Social.
Image Posts: Posts that contain one or more images.
Total Images: The total number of images across all posts.
Images With Alt: How many of those images include non-empty alt text.
Posts With All Images Alt: Posts where every image has alt text.

Formula

Accessibility Score = (AltCoveragePct x 0.8) + (PostCoveragePct x 0.2)

Where:

AltCoveragePct = (ImagesWithAlt / TotalImages) x 100
PostCoveragePct = (PostsWithAllImagesAlt / ImagePosts) x 100

Example:

100 images, 80 with alt → AltCoveragePct = 80%
20 image posts, 15 fully accessible → PostCoveragePct = 75%
Score = (80 × 0.8) + (75 × 0.2) = 64 + 15 = 79/100

Why does this matter?

Improves Inclusivity: Alt text ensures visually impaired users can engage with your content.
Boosts Engagement: Accessible posts often perform better because they’re usable by a wider audience.
Future-Proofing: Accessibility is increasingly a compliance and ethical requirement.

Best Practices for Alt Text

Be Descriptive: Explain what’s in the image, including context.
Avoid Redundancy: Don’t repeat captions or obvious details.
Keep It Relevant: Focus on what matters for understanding the post.

Example of good alt text:

“Screenshot of the new Cloudflare block page branded with Tophhie Cloud, showing access restriction details and a contact button.”

Next Steps

I’ll be publishing accessibility scores for accounts hosted on Tophhie Social soon, along with tips for improving them. If you’re a developer, consider automating alt text checks in your posting workflow.

TL;DR

The Accessibility Score is a simple yet powerful way to measure how well your Bluesky posts support users with assistive needs. Aim for 100% coverage - because accessibility isn’t optional.

Want access to your own accessibility score?

The Accessibility Score system has been integrated with the Tophhie Social domain and the Tophhie Cloud API! ✨

For any user hosting their repo on Tophhie Social, you can access your score by querying:

https://tophhie.social/accessibilityScore?did={did}

For example:

https://tophhie.social/accessibilityScore?did=did:plc:ggobmtqnjirtchpwgydxoecb

The score on the Tophhie Social domain is updated daily, at roughly midnight. If you'd like the live score as of that second, you can query the endpoint on the Tophhie Cloud API.