Like many other kinds of squash, zucchini is indeed safe for cats in moderation. (Oh, did you know zucchini was a type of summer squash? If not, you're welcome.)
Zucchini contains a number of healthy nutrients, such as vitamins A and C, along with plenty of dietary fiber. Vitamin A contributes towards good vision, growth and immune function, while vitamin C supports wound-healing and the production of collagen. The dietary fiber in zucchini can help regulate healthy bowel movements.
While zucchini doesn't contain any compounds that are toxic to cats, you should only feed it to them in moderation. Cats are obligate carnivores, which means their main diet should consist of meat. Nevertheless, occasionally supplementing meat-heavy diets with vegetables like zucchini can provide them additional nutrients and variety.
If you do feed your cat zucchini, make sure it's unseasoned, unbuttered, and baked or steamed. Seasonings and butter can cause stomach problems, and raw zucchini may be difficult for your cat to digest.
As always, before introducing a new food item into your pet's diet, consult with your veterinarian first. If your cat eats zucchini (or any food) and is showing signs of illness such as lethargy, diarrhea, or vomiting, reach out to your veterinarian immediately. If they require veterinary care related to eating any unsafe foods, pet insurance can help cover the cost of treatment.