If you die and have no valuable property, who is responsible for any debts that you have?

The Estate must pay.  If there is no money in the Estate then the debts are cancelled.  Be aware that creditors will come looking so do not try and hide money or assets.  Also if there ar co-signors etc they would still be responsible.

Your estate would be responsible to pay your debts after your death. If the estate has no assets, then the debts are extinguished as a matter of law. In other words, your creditors simply don't get paid and must write of any amounts owed to them. Niether heirs nor beneficiaries are responsible for paying debts that remain.