There are various open source tools on github but you would need to specify what you need to extract?

If you just look for addresses inside the wallet you can sometimes even use a hex editor.

Pywallet is widely used but doesnt always give you correct results if the wallet is damaged or is new. It sometimes need modification. If you ate a programmer you can always extract code from github and create your own custom reader.

It is even possinle to extract info from Android phones but that would require some forensic tools