AI Auto Alt Text Generator vs Auto Alt Text

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

This plugin implements the automatic creation of alt text for images uploaded to the media library. The alt text is generated at the time of uploading the image and it is also possible to generate the alt text for images already present in the media library. To generate the alt text, you can choose to use the artificial intelligence of OpenAI, Anthropic Claude, Google Gemini or Azure, or decide if you simply want to copy the title of the article where the image is uploaded or the name of the image. Clearly, using artificial intelligence will allow for a more accurate and useful alt texts. Features This plugin allows you to generate alt texts in the following ways: – using Openai APIs (the most recently released models and any other compatible model available on your account) – using Anthropic Claude API – using Google Gemini API – using Azure APIs for computational vision; – recovering the title of the image – recovering the title of the article in which the image is uploaded It can also fill in, on the fly, the missing alt texts of the images already published in your content, using the alt text stored in the media library. Getting Started After installing the plugin, click on the ‘Auto Alt Text’ menu item. Choice of Generation Method Select the Generation Method you prefer OpenAI’s APIs In your OpenAI account, retrieve the following data to enter on the options page: – API Key Once the API Key is saved, the list of the models available on your account is retrieved directly from OpenAI, so you can always choose among the up-to-date models. If the model you selected is retired by OpenAI, a notice is displayed in the administration area and the least expensive available model is used as a fallback until you choose a new one. Choose the model you want to use for generating the alt text. Enter a prompt for generating the alt text according to your needs. Claude Anthropic’s APIs In your Anthropic account, retrieve the following data to enter on the options page: – API Key Choose the model you want to use for generating the alt text. Enter a prompt for generating the alt text according to your needs. Google Gemini’s APIs In your Google AI Studio account, retrieve the following data to enter on the options page: – API Key Once the API Key is saved, the list of the models available on your account is retrieved directly from Google, so you can always choose among the up-to-date models. If the model you selected is retired by Google, a notice is displayed in the administration area and the least expensive available model is used as a fallback until you choose a new one. Choose the model you want to use for generating the alt text. Enter a prompt for generating the alt text according to your needs. Azure’s APIs On your Azure account, create a Computer Vision instance and retrieve the following data to enter on the options page: – Computer Vision API Key – Computer Vision Endpoint If you want to generate an alt text in English, save the options without filling in any other fields. If you want to generate an alt text in a different language, on your Azure account, create a Translator instance and retrieve the following data to enter on the options page: – Translator Instance API Key – Translator Instance Endpoint – Translator Instance Region After entering this data, save the options. Select the desired language and save the options again. Title of the article For this generation method, there are no options to set as the alt text will be generated by copying the title of the article in which the image is uploaded. In case the article is not uploaded as an attachment of an article, the “Title of the attachment” method will be used as a fallback. Title of the attachment For this generation method, there are no options to set as the alt text will be generated by copying the title of the image. Functioning Once the plugin is configured, each time an image is uploaded to the media library, an alt text will be automatically set based on the selected generation method. For images already in the media library, you can create bulk alt texts. Open the Media Library in the “list” view, select the images for which to generate the alt text, and choose the “Generate alt text” bulk action. (Depending on the number of images chosen and their weight, this may take some time.) You can also generate the alt text of a single image directly from the media library. Open the Media Library in “grid” mode, choose the image for which to generate the alt text, and click the “Generate alt text” button. In no time the alt text field will be overwritten by the generated description. Automatic alt text rendering in content Images that were inserted in your posts and pages before the alt text was generated keep the empty alt attribute saved in the content, even after the media library has been filled. By enabling the “Automatically render alt text in content” option, when a page is displayed the plugin looks at every image of the content and, for those without an alt text, it writes the alt text stored in the media library (when available). Images that already have an alt text are never touched, and your saved content is not modified in any way: the alt text is only added to the rendered HTML. The option is disabled by default and it is independent of the chosen generation method. Developers can also control this behaviour with two filters: aatxt_content_alt_text_enabled to skip the processing for a specific request, and aatxt_content_image_alt_text to filter the alt text before it is written into the image tag. WP-CLI If you prefer generating alt text in batch (e.g., to avoid processing in the Media Library UI), you can use WP-CLI. This is the recommended way to work on a large media library: the bulk action of the Media Library runs inside a single web request, so depending on your server settings (PHP max_execution_time, PHP-FPM request_terminate_timeout, web server or proxy timeouts) it can be interrupted before all the selected images have been processed. WP-CLI is not affected by those limits, shows a progress bar and can be resumed with --offset. Generate alt text for a list of attachment IDs: wp auto-alt-text generate --ids=123,456,789 Process all image attachments in batches: wp auto-alt-text generate --all --limit=200 --offset=0 wp auto-alt-text generate --all --limit=200 --offset=200 Dry run (no metadata updates): wp auto-alt-text generate --ids=123,456 --dry-run Force overwrite of existing alt text (even if “Keep existing alt text” is enabled): wp auto-alt-text generate --all --limit=200 --offset=0 --force Notice: If you choose one of the methods that involves the use of external APIs, the upload times for images in the media library might increase because it requires sending a request to the APIs, waiting for the external server to process, and waiting for a response. Logging If the generation of the alt text via AI is set, in case of errors, to avoid blocking the editorial work, the image is loaded anyway but without the alt text being compiled. When a call to the OpenAI, Anthropic, Gemini or Azure API fails, a record containing the error message is saved in a custom database table. In this case, the cause of the error can be seen on the Auto Alt Text -> Error log page. External Services This plugin uses the following external services alternatively: OpenAI Selecting the generation method “OpenAI’s APIs” will use the API services of OpenAI. This plugin does not collect any information from your OpenAI account. The data transmitted to OpenAI mainly consists of the image files uploaded to your website and the specified prompt. For accurate information on privacy and conditions of use, please consult the privacy policy and terms and conditions directly on the official website. It is also advisable to check the costs and usage statistics of the API service on the OpenAI website. Anthropic Claude Selecting the generation method “Anthropic’s APIs” will use the API services of Anthropic. This plugin does not collect any information from your Anthropic Claude account. The data transmitted to Anthropic Claude mainly consists of the image files uploaded to your website and the specified prompt. For accurate information on privacy and conditions of use, please consult the privacy policy, terms and conditions for consumers and terms and conditions for commercial directly on the official website. It is also advisable to check the costs and usage statistics of the API service on the Anthropic website. Google Gemini Selecting the generation method “Google Gemini’s APIs” will use the API services of Google Gemini. This plugin does not collect any information from your Google account. The data transmitted to Google mainly consists of the image files uploaded to your website and the specified prompt. For accurate information on privacy and conditions of use, please consult the privacy policy and terms of service directly on the official website. It is also advisable to check the costs and usage statistics of the API service on the Google AI website. Azure Selecting the “Azure’s APIs” generation method will use the API services of Microsoft Azure. This plugin does not collect any information from your Azure account. The data transmitted to Azure consists mainly of image files uploaded to your website. For accurate information on privacy and conditions of use, please directly consult the privacy policy and terms and conditions on the official website. It is also advisable to check the costs and usage statistics of the API service on the Microsoft Azure’s website. Encryption Constants We strongly recommend defining the new plugin-specific constants in your wp-config.php: define( 'AATXT_ENCRYPTION_KEY', 'a_random_string_of_at_least_64_characters' ); define( 'AATXT_ENCRYPTION_SALT', 'another_random_string_of_at_least_64_characters' ); You will find these two define(…) lines already generated for you on the Auto Alt Text » Options page – simply copy & paste them before the /* That's all, stop editing! Happy publishing. */ line in your wp-config.php. If you choose not to add them, the plugin will continue to work normally, but it will fall back to using your WordPress LOGGED_IN_KEY / LOGGED_IN_SALT, which may break if those salts are ever changed. Disclaimer Auto Alt Text is a plugin that helps users automatically generate Alt Texts of their images using AI services such as OpenAI’s ChatGPT or Microsoft Azure. Users need their own API key and must follow the rules set by the AI service they choose. By using Auto Alt Text, users agree to watch and manage AI-made content and address any issues or misuse. AI Engine developer and related parties are not responsible for any problems or losses caused by the use of the plugin or AI-generated content. Credits A big thank you to everyone who has improved this plugin with a pull request: joshuafredrickson – native WP-CLI support for batch alt text generation, and the Media Library bulk action redirect fix that preserves pagination and filters The full list is available on the contributors page. Contributions are welcome: feel free to open an issue or a pull request on GitHub.