Forensically is a set of free tools for digital image forensics. It includes clone detection, error level analysis, meta data extraction and more. It is made by Jonas Wagner.
Exemple clone detection
The clone detector highlights similar regions within an image. These can be a good indicator that a picture has been manipulated using the clone tool. Note that this tool is a beta version and not yet very refined.
It is free and easy to use, a useful tool against rumours and misinformation.