API key: In Plugins > WriteAlt, enter your own WriteAlt key in the private writealt_api_key setting (use the separate dev value for testing). Never expose it in a page.
New uploads: On an uploader's value-changed workflow, call WriteAlt - Process Uploaded Image with the saved image URL and an empty Job ID. Save the returned job_id immediately. Check again with that SAME saved ID until ok and ready are yes. Then save alt_text to your image record and bind the Image element's ALT tag to that field. Preserve existing descriptions; never automatically resubmit a pending or ambiguous job.

All existing database images: Add alt_text and writealt_job_id fields to each image-bearing data type. Create a private backend workflow for one record, using the same start/save/check flow. Use Bubble's Schedule API workflow on a list on a filtered search of records missing alt text, with an interval to pace requests. Test a few records before a large run. The plugin also has Prepare Image List, Parse Image CSV and bounded batch actions for mapped URLs or CSV. It cannot discover unrelated database types, static page images or unlinked File Manager uploads automatically. Each app owner must map their fields and save workflows. The optional Media Manager is an app-page component, not a Bubble editor extension. WriteAlt credits and Bubble workload apply.