Adding Alt Text to Images in Publlish
Learn how to add alt text to images in your social media posts through Publlish. Improve accessibility for visually impaired users and learn which platforms support alt text via the publishing API.
Alt text (alternative text) is a written description of an image that serves two important purposes: it makes your content accessible to people using screen readers, and it helps search engines and platform algorithms understand what your images show.
Adding alt text is a small effort with meaningful impact — especially for marketing teams and agencies whose clients care about brand accessibility and inclusivity.
What is Alt Text?
Alt text is a short description of an image that:
- Is read aloud by screen readers for visually impaired users
- Displays in place of the image if the image fails to load
- Is indexed by search engines and social platform algorithms as context about your content
- Shows up in accessibility audits and WCAG compliance checks
Good alt text describes what's in the image concisely and accurately — it doesn't need to be a paragraph, but it should be specific enough that someone who can't see the image understands what it shows.
How to Add Alt Text in Publlish
- In the Publlish composer, after uploading an image, click the Alt text option (often represented by an accessibility icon or a text field beneath the image preview)
- Type your alt text description
- Save — the alt text will be included when the post publishes to platforms that support it
Platform Support for Alt Text via Publlish
| Platform | Alt text support via Publlish | Notes |
|---|---|---|
| ✅ Yes | Available for feed posts and carousels | |
| ✅ Yes | Available for image posts | |
| X (Twitter) | ✅ Yes | Up to 1,000 characters |
| ✅ Yes | Available for image posts | |
| TikTok | ❌ No | TikTok does not expose alt text via API |
| YouTube | ❌ No (for videos) | Video descriptions serve a similar purpose |
For platforms where alt text isn't supported via the API, consider including descriptive context in the post caption as an alternative.
Writing Good Alt Text
Be specific and descriptive. "A photo" is not useful alt text. "A marketing team reviewing a social media calendar on a laptop in a bright office" is.
Don't start with "image of" or "photo of." Screen readers already announce that it's an image — starting with "image of" is redundant. Just describe what's shown.
Include text that appears in the image. If your image has a quote, statistic, or CTA overlaid as text, include that text in the alt description so screen reader users don't miss it.
Keep it concise. Aim for 50–125 characters for most images. Longer descriptions (up to the platform limit) are appropriate for complex infographics or data visualisations.
Don't keyword-stuff. Alt text is for accessibility, not SEO manipulation. Write it for a human listener, not a search engine.
Alt Text Examples
| Image | Poor alt text | Good alt text |
|---|---|---|
| Product photo | "product" | "Glass bottle of Revive vitamin C serum on a white marble surface" |
| Team photo | "our team" | "Five Publlish team members smiling in front of a whiteboard with post-it notes" |
| Infographic | "infographic" | "Infographic showing 5 steps to grow Instagram from 0 to 10,000 followers. Step 1: Post Reels daily. Step 2: Use 5 niche hashtags..." |
| Quote graphic | "quote" | "Quote: 'Consistency beats perfection every time.' — Sara Chen, CMO of BrandX" |
Alt Text for Carousels
For carousel posts (multiple images), add separate alt text for each slide:
- Slide 1: describe the first image
- Slide 2: describe the second image
- And so on
Each slide is a separate image and needs its own description.
Why Alt Text Matters for Agency Clients
If you're managing social media for clients, building alt text into your content process shows professionalism and protects clients against accessibility complaints. Increasingly, brand guidelines include accessibility requirements for all published content.
A simple rule for your workflow: every image post gets alt text before it's approved and scheduled. Make it part of your content checklist alongside caption and hashtags.
Frequently Asked Questions
Does adding alt text affect post reach or algorithm performance? It can positively influence how platforms understand and categorise your content — but the primary reason to add alt text is accessibility, not algorithmic gain.
Is alt text required? It's not enforced as mandatory on social platforms, but it is required for WCAG 2.1 AA accessibility compliance — which is increasingly expected by brands and corporates. It's good practice regardless of requirements.
What's the character limit for alt text on each platform? Instagram: 420 characters. X: 1,000 characters. Facebook and LinkedIn: varies but generally sufficient for descriptive alt text.
Do I need to add alt text for decorative images? For purely decorative images with no informational content, alt text can be left empty (or set to empty string "") — screen readers will skip it. For any image that carries meaning or information, alt text is needed.