Preheat your oven to 350°F. Grease a loaf pan or line it with parchment paper.
In a large mixing bowl, combine the flaked salmon, breadcrumbs, chopped onion, and chopped celery.
In a separate bowl, whisk together the mayonnaise, eggs, Dijon mustard, Worcestershire sauce, dill weed, garlic powder, salt, black pepper, and lemon juice until smooth.
Pour the wet mixture into the dry ingredients and mix until well combined. If using, fold in the chopped parsley.
Transfer the mixture to the prepared loaf pan, pressing it down gently to shape it.
Bake in the preheated oven for 45-50 minutes, or until the loaf is firm and golden brown on top.
Let the salmon loaf cool for about 10 minutes before slicing and serving.