Google Vision AI - Cloud Vision API provides a comprehensive set of capabilities including object detection, ocr, explicit content, face, logo, and landmark detection.
API List - A collective list of APIs. Build something.
Amazon Rekognition - Add Amazon's advanced image analysis to your applications.
Abstract APIs - Simple, powerful APIs for everyday dev tasks
CaptionBot by Microsoft - Analyzing and describing images by a bot
Phantombuster - A marketplace of simple to use no-code APIs