What else to use to test doneness in muffin if not using a toothpick?

If you don't have a toothpick to test muffin doneness, you can use a cake tester, a thin skewer, or the tip of a knife. Alternatively, gently press the top of the muffin; if it springs back, it's likely done. You can also check for a golden-brown color on the top and ensure the sides are pulling away slightly from the muffin tin.