OSX FileMerge

Just found the FileMerge tool in with the developer tools (in /Developer/Applications/Utilties if you’ve got the Developer Tools installed - free download from Apple after you’re registered). It’s a rather nice GUI version of the diff command line tool for comparing the differences between two files, but critically it does this rather sweet line scrolling thing where it keeps the two side by side documents lined up even when passing the differences - it makes it really clear and easy to see the changes.

You can use it to merge (as you may have guessed from the name) the files and save that merger as a new file (overwriting one of the two you’re comparing if you want). It takes a moment to “get” the merging, you choose an action and select the copy you want to preserve i.