I am a salaried employee in California, exempt from the FLSA rules and protections, working as a software quality assurance engineer. In the last 10 years I have seen companies increase pressure on exempt employees to work 50 hours a week or more. At my last job, most engineers were working 10-14 hours per day plus occasional weekends. (My experience with working this long is that it eliminates most enjoyment from life, weakens my marriage and family, and hurts the community.)

Googling for labor law, I found rules to limit the number of hours per week, but inevitably none apply to exempt workers. My question is whether there are any laws that protect exempt employees from being abused by their employers? Can you recommend a website that specifies what federal and California laws protect exempt workers?

Neither state nor federal law limits the number of hours an exempt employee can be required to work, and might I add that 50 hours per week is not at all uncommon for an exempt employee. Nor would 60 or even 70.

You may be exempt from the FLSA rules, but California has additional protections. Given that you are paid a salary, you are probably not exempt and thus are subject to overtime rules. In general a software quaility assurance engineer will be non-exempt. However, job titles are not useful if you don't actually perform that type of work. If you do perform QA work, you are likely entitled to overtime.