Preheat oven to 325 degrees. Line a loaf pan with parchment paper. Whisk together eggs, vanilla extract, lemon juice, lemon zest, and butter.
In a separate bowl mix the almond flour, coconut flour, salt, baking powder, and low carb sweetener. Set aside.
Fold in the dry ingredients with the wet. Fold the zucchini into the batter and combine.
Transfer to the loaf pan and bake for about 30 minutes. If it’s browning too much toward the end of bake time, cover with foil. A toothpick inserted in the middle will come out clean when cooked. Place on a wire rack to cool.