been using this cool program securdat for 5 or 6 years.

It monitors folders and stores copies every time you make a change to a file in them. e.g. if you are editing abc.MQ4 then every time you save you will have abc[0001].mq4, abc[0002].mq4, etc.

useful if you make a mistake.

it is shareware but will continue to work in crippled mode... only monitor one folder or its subfolders. If all your code is in one folder or its subfolders, then it works just fine except a simple nag screen when windows starts up.

http://www.pa-soft.com/frameenglish.htm

also, you can use winmerge as a diff tool to see the differences between the files. This is useful if you are trying to figure out what exactly is different between abc.mq4 and abc[0074].mq4

winmerge is also great because you can actually diff entire folders too.

http://winmerge.sourceforge.net/

winmerge is free

note: if anyone knows a program that works like securdat but w/o a nag screen... i.e. freeware then please post a link. But I have evaluated many every couple of years and securdat is the only one I tested that was designed intelligently. It was made by a programmer for programmers.

note 2: if you are worried about space, you can set the number of backups to make. I think it can backup into zip files also, but can't remember for sure. But for me it would be much smarter to just use winxp to compress the securdat backups folder. which is what I do. text files compress very well, so it will save a lot of space.