Connor Bulmer

AI Auto Alt Text Generator is a lightweight, privacy-conscious plugin that uses OpenAI vision-capable models (defaulting to GPT-5.4 nano, with GPT-5.4 mini and legacy GPT-4o mini options) to create meaningful, screen-reader-friendly alt text and SEO-friendly titles for your images. Whether you add a single image, bulk-process your library, or just want a one-click fix in the Media Library, the plugin handles it all – no manual effort required.
This solution is far cheaper than many alternatives because it cuts out the middle-person. You’ll just need to bring your own OpenAI API key.
<h3>✨ Key features</h3>
<ul>
<li>Automatic alt text on upload – set-and-forget accessibility.</li>
<li>Optional automatic image titles – improve SEO with descriptive titles.</li>
<li>One-click manual generation – “Generate Alt Text & Title” button in the Media Library.</li>
<li>Bulk update tool – batch-process existing images, including those that only have filename-based alt text, with a configurable pause between batches.</li>
<li>Prompt fine-tuning – supply site-wide context and optionally include the image file name.</li>
<li>Model selection – default to GPT-5.4 nano (fastest & cheapest) or switch to GPT-5.4 mini for higher quality; legacy GPT-4o mini and GPT-5 mini/nano remain available.</li>
<li>Image size & detail control – choose the resolution and level of visual detail sent.</li>
<li>Developer-friendly – filters and actions to customise prompts, models and output, plus optional outgoing webhooks.</li>
<li>WordPress Abilities API – registers a <code>generate-alt-text</code> ability (WordPress 6.9+/7.0) so core AI, agents and automation tools can generate alt text.</li>
<li>No extra servers – data flows only between your site and OpenAI; nothing is stored off-site.</li>
<li>Multilingual output – choose English (UK), English (US) or other popular languages. (English US is the default.)</li>
</ul>
<h3>🧭 Where to find the bulk tool</h3>
<ul>
<li>Tools → Bulk Alt Text Update</li>
<li>Media → Bulk Alt Text Update (shortcut that redirects to the Tools page)</li>
<li>Settings → Alt Text Generator includes a button linking straight to the bulk page</li>
</ul>
<h3>🧠 How it works</h3>
<ol>
<li>When an image is uploaded (or manually chosen), the plugin creates a temporary public URL for that image.</li>
<li>It sends the image – plus optional context such as the parent post title, your custom site context and the file name – to your selected OpenAI vision model.</li>
<li>OpenAI returns a concise description.
<ul>
<li>Alt text is stored in WordPress’ native <code>_wp_attachment_image_alt</code> field.</li>
<li>(Optional) The returned title is stored as the attachment post title.</li>
</ul>
</li>
<li>Nothing is cached or stored on OpenAI’s side; only the final strings live in your database.</li>
</ol>
<h3>Settings overview</h3>
<ul>
<li>OpenAI API Key – Required to connect to OpenAI.</li>
<li>OpenAI Model – GPT-5.4 nano (default), GPT-5.4 mini, or legacy GPT-4o mini / GPT-5 mini / GPT-5 nano.</li>
<li>Image Size to Send – Thumbnail, Medium, Large, or Full.</li>
<li>Image Detail Quality – ‘Low’ or ‘High’ (Low uses fewer tokens).</li>
<li>Bulk batch size – Number of images per batch (lower values reduce rate-limit risk).</li>
<li>Site Context – Optional free-form prompt guidance (brand voice, niche, etc.).</li>
<li>Send Image File Name – Include file name in the prompt for extra context.</li>
<li>Automatically Generate Title – Add descriptive titles alongside alt text.</li>
<li>Use full context for image titles – When enabled, title generation includes site context and file name (uses more tokens).</li>
<li>Bulk optimiser delay (seconds) – Pause between batches during bulk runs.</li>
<li>OpenAI request timeout (seconds) – Max wait time for OpenAI responses (10–120s) to reduce timeout failures on slower hosts.</li>
<li>Output Language – Default English (US). Choose English (UK) for British spellings or another popular language; outputs (alt text and titles) will be generated in the selected language.</li>
<li>Webhook URL & signing secret – Optionally POST generated alt text/titles to an external endpoint (with an optional HMAC-SHA256 signature) for automation and logging.</li>
</ul>
<h3>Developers</h3>
The plugin is extensible via standard WordPress hooks, an outgoing webhook, and the WordPress Abilities API.
Filters
<ul>
<li><code>aatg_alt_text_prompt</code> ( $prompt, $post_ID, $context ) – customise the alt-text prompt.</li>
<li><code>aatg_image_title_prompt</code> ( $prompt, $post_ID, $context ) – customise the title prompt.</li>
<li><code>aatg_openai_request_payload</code> ( $payload, $context, $messages ) – customise the full OpenAI request (model, messages, reasoning effort).</li>
<li><code>aatg_generated_alt_text</code> ( $alt_text, $post_ID ) – filter alt text before it is saved.</li>
<li><code>aatg_generated_title</code> ( $title, $post_ID ) – filter the title before it is saved.</li>
<li><code>aatg_is_low_quality_alt</code> ( $is_low, $alt, $post_ID ) – control which existing alt text the bulk tool regenerates.</li>
<li><code>aatg_webhook_payload</code> ( $payload, $post_ID, $result ) – customise the outgoing webhook body.</li>
<li><code>aatg_supported_image_extensions</code> ( $extensions ) – customise which image formats are sent to OpenAI (default: PNG, JPEG, GIF, WebP).</li>
</ul>
Actions
<ul>
<li><code>aatg_after_alt_text_generated</code> ( $post_ID, $alt_text )</li>
<li><code>aatg_after_title_generated</code> ( $post_ID, $title )</li>
<li><code>aatg_after_generation</code> ( $post_ID, $result )</li>
</ul>
Outgoing webhook
Set a Webhook URL under Settings → Integrations & Webhooks to receive a non-blocking JSON POST after each generation. If a signing secret is set, requests include an <code>X-AATG-Signature: sha256=…</code> header (HMAC-SHA256 of the body) so your endpoint can verify authenticity.
WordPress Abilities API
On WordPress 6.9+ the plugin registers the ability <code>ai-auto-alt-text/generate-alt-text</code> (input: <code>attachment_id</code>) so WordPress core AI, agents, MCP servers and automation tools can generate alt text programmatically. Execute it with <code>wp_get_ability( 'ai-auto-alt-text/generate-alt-text' )->execute( array( 'attachment_id' => 123 ) )</code>.
<h3>External services</h3>
This plugin connects to the OpenAI API to generate alt text and (optionally) image titles.
<ul>
<li>Endpoint: <code>https://api.openai.com/v1/chat/completions</code></li>
<li>When called:
<ul>
<li>On image upload (automatic)</li>
<li>Via “Generate Alt Text & Title” button in Media Library (manual)</li>
<li>Via Tools → Bulk Alt Text Update (bulk)</li>
</ul>
</li>
<li>Data sent: image URL, optional file name, optional site context, optional parent post title</li>
<li>Terms: <a href="https://openai.com/policies/terms-of-use" rel="nofollow ugc">https://openai.com/policies/terms-of-use</a></li>
<li>Privacy: <a href="https://openai.com/policies/privacy-policy" rel="nofollow ugc">https://openai.com/policies/privacy-policy</a></li>
</ul>
If you configure a Webhook URL, generated alt text/titles (and the image URL) are also sent to that endpoint you control.

AI Auto Alt Text Generator

Automatically generates alt text and image titles for your WordPress media uploads with selectable OpenAI models (defaulting to GPT-5.

neil williams

Images without alt text are a problem for accessibility (screen readers) and SEO. 
This lightweight plugin automatically adds alt attributes where they are missing:
<ul>
<li>Inside post content → uses the current post title. </li>
<li>For images loaded via <code>wp_get_attachment_image()</code> → uses the image filename (without extension). </li>
</ul>
If an image already has alt text, the plugin leaves it untouched.
No settings, no configuration — just activate and your site is more accessible.
<h3>Features</h3>
<ul>
<li>Improves accessibility by ensuring images have alt text. </li>
<li>Helps SEO by filling in descriptive alt attributes. </li>
<li>Post/page content images get the post title. </li>
<li>Template images (e.g. theme calls) get the filename. </li>
<li>Super lightweight and fast.</li>
</ul>

Auto Alt Images

Automatically fills in missing alt attributes for images using the post title or filename.

AI Auto Alt Text Generator vs Auto Alt Images