If you have tomato paste, dilute it with water or broth to achieve a similar consistency to tomato sauce. Use a tablespoon of tomato paste mixed with water as a 1:1 substitute for tomato sauce.
Crushed, diced, or whole canned tomatoes can be blended or crushed further to make a quick sauce. Simmer them with some seasonings like basil, oregano, garlic, and onion powder to enhance the flavor.
If you have fresh tomatoes, chop or puree them and cook them down to a sauce-like consistency. Add some olive oil, herbs, and spices to enhance the flavor.
While it's sweeter than tomato sauce, ketchup can be used in a pinch as a substitute. Mix it with a bit of vinegar or lemon juice to balance the sweetness and adjust the taste.
Depending on the dish you're preparing, barbecue sauce can work as a substitute due to its tomato base. However, note that it might have a smoky or sweet flavor, so adjust other seasonings accordingly.
Salsa, especially if it's on the chunkier side, can work in recipes that call for tomato sauce. Puree or strain it for a smoother consistency before using it as a substitute.
These sauces are similar to tomato sauce but might contain additional ingredients like herbs, spices, and vegetables. They can be used as a substitute, but be mindful of their flavors when incorporating them into your dish.
In some recipes, you can substitute tomato sauce with vegetable or chicken broth to provide moisture and flavor. It won't replicate the tomato flavor, but it can work as a liquid base in certain dishes.