Most county law libraries have an up to date and usable dissomaster. There is a law library in San Jose near the courthouse but you'll have to google it for the exact address.
Christopher Robert CarlingConstruction / Development LawyerAlameda, CA ·
If you have access to the internet (which I guess you do because you're posting here), then you can find a child support calculator supplied by the State of California here:
https://www.cse.ca.gov/ChildSupport/cse/guidelineCalculator
You can also download a trial version of the DissoMaster software here:
http://cflr.com/download/DMUpdate.php