I work in California for a company that is based in Delaware. I am asked to sign a non-compete agreement that would prevent me from doing what I do today for 18 months after termination anywhere in the world.
I have read that these types of agreement are not enforceable in California and I would like to know if the fact that the company is from Delaware makes any difference.
They cannot control anything that happens following the termination of a contract as it is terminated.
As Answers OnStartups does not have lawyers and your question is primarily a legal issue you would be better off seeking profession legal advice.
It makes no difference. You can still be sued for a breach of contract in Delaware, and the judgement against you will still be enforceable (including levies and garnishes in California).
Whether or not the non-compete itself is enforceable or not (i.e.: whether the courts will actually rule against you in case you're sued) is an entirely different issue.
To clear up the confusion: non-compete provisions are generally void in California. But they're not in Delaware. The full faith and credit clause of the US Constitution demands that States uphold other States' laws. That means that you can be sued based on the DE law, even if you're in CA, if the contract is based on the DE law and jurisdictions. In the past, CA courts ruled that even out of state clauses cannot be enforced in California, but there are 2 issues with this:
Bottom line: don't take this lightly. Don't listen to people who say "It didn't happen to me, so it won't happen to you". You don't want to be the one that it does happen to.
I've signed these very agreements before, and broken them. They are difficult to enforce in general. As someone with personal experience in this matter as well as a decent laypersons understanding of employment law, I wouldn't worry about this non-compete at all unless you breech and then go move to DE to work for a different DE company who is a competitor of your original company.