I came across the Rekognition tool from Amazon in 2017 but never used it or anything. Today I needed to figure out a way to identify profile images in my app and check if they are inappropriate or not and I found that Amazon Rekognition provides a web service to do exactly that using A.I algorithms to parse the image and respond whether or not the image has suggestive, inappropriate, explicit, nude etc with a confidence percentage.
You can find out more about it here – https://aws.amazon.com/about-aws/whats-new/2017/04/detect-explicit-or-suggestive-adult-using-amazon-rekognition/
Try out the tool after logging into your AWS console – https://us-west-2.console.aws.amazon.com/rekognition/home?region=us-west-2#/image-moderation
Here is the REQUEST and RESPONSE