HDRMerge is described as 'HDR raw exposure merging : HDRMerge combines two or more raw images into a single raw with an extended dynamic range'. There are six alternatives to HDRMerge for various platforms. The best alternative is WidsMob HDR.
The list of alternatives was last updated Mar 22, 2019
Simple and advanced HDR photo editor to recreate high dynamic range photos as eye-view. Advanced tone mapping algorithm, customize HDR parameters, auto align and adjustment, support both JPEG and RAW files. View 33 alternatives to WidsMob HDR