Following a few tips while boiling eggs will mean the difference between beautiful boiled eggs and ugly, cracked monster-looking eggs. These tips are especially important if you intend to dye the eggs for Easter or other holidays or if you intend to slice them in half for deviled eggs. While the part that seeps out of the shell can be trimmed so the outside still looks presentable, the water that gets into the shell changes the texture and flavor somewhat as the egg cooks. To make the tastiest boiled eggs, it's best to prevent the shells from cracking.
Use eggs that have been in the refrigerator longer. The older an egg gets, the smaller the contents inside become and this will keep the finished egg from swelling inside as it cooks, causing the shell to crack.
Allow the eggs to come to room temperature before cooking if you are going to boil your water first. Adding cold eggs to warm or hot water increases the chances that they will crack.
Lower the eggs slowly into the pot using a slotted spoon as dropping them too quickly could crack them. Do not overfill the saucepan with eggs. The eggs need room to move somewhat while boiling and the more interaction they have with other eggs, the greater the chances they will crack while cooking.
Place the eggs into the saucepan and cover with cold tap water. The water should rise 1/2 inch above the top of the eggs.
Add a teaspoon of vinegar to the water to seal any small cracks that may already be present or that may occur as a result of the eggs tapping each other or the pan. This will prevent any larger cracks from forming.
Simmer the eggs on a lower temperature. This will eliminate the excess movement cause by boiling them too rapidly, further reducing chances for the shells to crack.