Preheat oven to 350°F (175°C). Grease or line a muffin tin.
In a bowl, mix flour, baking soda, baking powder, cinnamon, nutmeg, and salt.
In another bowl, whisk together eggs, sugar, oil, and vanilla until smooth.
Stir in the grated zucchini.
Fold dry ingredients into the wet mixture until just combined.
Add chocolate chips, nuts, or raisins if desired.
Spoon batter into muffin cups, filling about ¾ full.
Bake for 18–22 minutes, or until a toothpick inserted in the center comes out clean.
Cool for 5 minutes in the pan, then transfer to a wire rack.