Base & dissolve: In a medium saucepan over medium heat, whisk together ketchup, vinegar, brown sugar, and molasses until the sugar dissolves.
Season: Stir in Worcestershire, chili powder, smoked paprika, garlic powder, onion powder, black pepper, and cayenne.
Thin: Add water and stir to combine.
Simmer: Reduce to low and simmer 15–20 minutes, stirring occasionally, until the sauce thickens and flavors meld.
Taste & adjust: Add more vinegar for tang, more brown sugar for sweetness, or a pinch more cayenne for heat.