KeepSafe - Keep your entire photo library safely stored in an encrypted private cloud.
Yandex.Images - search for images on the internet, search by image
Hide Secrets - Hide Secrets is an app that allows hiding everything they deem confidential on their smartphone.
TinEye - Reverse Image Search to help find an image's source, duplicates or altered versions.
Hexlock - Security app locker keeps apps private with smart profiles for any situation
SauceNAO - SauceNAO is a reverse image search engine.