Open and drain the canned chicken thoroughly.
Place the drained chicken in a mixing bowl and use a fork to shred it into smaller pieces.
Add the mayonnaise to the bowl and stir until the chicken is evenly coated.
Mix in the chopped celery, sweet relish, and onion powder.
If using optional ingredients, gently fold in the hard-boiled egg, grapes, diced apple, mustard, and paprika.
Season the salad with salt and black pepper to taste.
Stir gently until everything is combined and the texture is creamy but not too wet.
For best flavor, cover and chill in the refrigerator for 10 to 15 minutes before serving.
Serve on sandwiches, crackers, lettuce leaves, or however you like.