OpenCV - OpenCV is the world's biggest computer vision library
IMG.LY - Power Your Apps with IMG.LY | The Leading Provider of Design, Photo, and Video Editing SDKs
Microsoft Computer Vision API - Extract rich information from images and analyze content with Computer Vision, an Azure Cognitive Service.
Sightengine - Effortless moderation of user-submitted photos. Instantly detect nudity and adult content with our easy-to-use API, for a fraction of the cost of human moderation
Amazon Rekognition - Add Amazon's advanced image analysis to your applications.
PicPurify - Real-time image moderation API which accurately detects inappropriate images containing specific elements like porn, nudity, violence, drugs, weapons... Our goal is to identify those images in user generated content and remove them automatically.