Of all the types of cooked eggs, hard-boiled are definitely the most hardy. Most eggs will go off pretty soon after they have been cooked, but hard-boiled eggs can actually be safe to eat for up to 1 week if they are stored in the refrigerator. This is why hard-boiled eggs are such a popular choice when it comes to meal preparation.
However, for your hard-boiled eggs to be safe to eat for this length of time you will have to take careful precautions in the preparation process. To do this, you should cook your eggs and cool them before placing them in the refrigerator within 2 hours of cooking. You should also keep the shells on the eggs and store them within an airtight container or in an egg carton. Only then will they be safe to eat for up to 1 week.