The Unsplash API - No-limits, do-what-you-want API for access to 200K+ HD pics.
Flico - Add visual search to your Chrome browser
PublicAPIs - Explore the largest API directory in the galaxy
Vize.ai - custom vision API - Image recognition API. Use your own Artificial Intelligence
API List - A collective list of APIs. Build something.
Google Vision AI - Cloud Vision API provides a comprehensive set of capabilities including object detection, ocr, explicit content, face, logo, and landmark detection.