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.

altagonist

Bloemist

Alt tags matter. They help visually impaired users understand your images, improve your search engine rankings, and are a basic requirement for web accessibility. Writing them by hand for every image in your media library is tedious. Altagonist takes care of it for you.
Point it at your images, click Generate, and get descriptive alt tags written by AI, saved directly into your WordPress media library.
How it works
<ol>
<li>Open the Altagonist page in your WordPress admin</li>
<li>Browse your media library and select one or more images</li>
<li>Click Generate. Image info is sent to the Altagonist API and an alt tag comes back</li>
<li>The alt tag is saved to your media library, just like you typed it yourself</li>
</ol>
Features
<ul>
<li>AI-powered alt tag generation using computer vision</li>
<li>Supports JPEG, PNG, GIF, and WebP. SVG, AVIF, TIFF, and BMP are converted automatically</li>
<li>Bulk generation: select multiple images and process them all at once</li>
<li>Three quality levels (Lite, Medium, High). Higher quality uses more page context for better results</li>
<li>70 languages supported</li>
<li>Auto-generate on upload: enable in Settings to tag images the moment they are uploaded</li>
<li>Filters to show only images with missing alt tags so you can close gaps quickly</li>
<li>Alt tags are saved to the standard <code>_wp_attachment_image_alt</code> field, fully compatible with all themes and plugins</li>
</ul>
External service
Images are processed externally. When you trigger alt tag generation (manually or via auto-generate on upload), the following data is sent:
<ul>
<li>The image URL (or the image itself as base64 if the URL is not publicly reachable)</li>
<li>Site name, page title, and page content (amount depends on the quality setting)</li>
<li>Selected language and quality level</li>
<li>Your license key and site URL</li>
</ul>
No data is sent unless you actively trigger generation or have auto-generate on upload enabled. Images are processed in real-time and are not stored.
<ul>
<li><a href="https://altagonist.com/terms" rel="nofollow ugc">Terms of Service</a></li>
<li><a href="https://altagonist.com/privacy" rel="nofollow ugc">Privacy Policy</a></li>
<li><a href="https://altagonist.com" rel="nofollow ugc">Altagonist website</a></li>
</ul>

Altagonist

Generate accurate, SEO-friendly alt tags for your WordPress images using AI. Make your site more accessible in seconds.

AI Auto Alt Text Generator vs Altagonist