Download PATCH – Updating System [BASIC] FREE Unity. 

P.A.T.C.H. is a professional solution for applications/games patching and updating.
It contains all features you need: installer, patcher, launcher, repairer, patches creator, FTP uploader, etc. An all-in-one, smart and clean solution!
It can generate very small patches thanks to its included file binary diffing algorithm.
What does it mean? It means that if you change only 5 bytes in your game, P.A.T.C.H. will create a patch that will change only those 5 bytes on users’ builds, instead of downloading the entire edited file.
Your users will be able to maintain updated their application copies with no pain or headaches, by saving bandwidth and time. Your users will love you!
In addition, you will be able to create small-sized patches (and upload them) quickly with included tools!

It includes Unity integrated tools and standalone version (if someone prefers to use it).

You can export Unity integrated P.A.T.C.H. for each supported platform, thanks to Unity. Standalone P.A.T.C.H. can be compiled for each platform you need with Xamarin/Mono. You can check out this feature in P.A.T.C.H. documentation.