Yes — Ninja, Tower, Tefal and Philips all confirm in their published guidance that foil is safe to use in their air fryers, as long as you follow a few basic rules that come down to protecting airflow and the non-stick coating rather than the foil itself being dangerous.
The Rules
Never let foil cover the entire base of the basket or block the air holes — this stops hot air circulating properly, can cause uneven cooking, and in some models can trigger the appliance to run hotter than intended as it tries to compensate. Weigh foil down with food so it doesn't get pulled into the heating element by the fan, which is a genuine fire risk if a loose sheet lifts and touches the element.
When to Use It
Foil is genuinely useful for lining the basket under messy marinated meat (easier cleanup than scrubbing sauce off a basket) or for shielding delicate items like fish from direct contact with a hot metal surface. For most everyday cooking — chips, roast potatoes, sausages — you don't need it at all, and using it unnecessarily can actually reduce crisping by blocking some of the airflow that makes air frying work in the first place.
Foil vs Parchment Liners
Purpose-made perforated parchment liners are often a better choice than foil for everyday use, because the holes are pre-cut to maintain airflow and they're generally cheaper to replace often. Foil is better suited to occasional use where you specifically want to block airflow to one area, like shielding a delicate garnish from direct heat.
What About Non-Stick Coating Damage?
Foil itself doesn't damage a non-stick basket if used correctly, but acidic foods (tomato-based sauces, citrus marinades) left in prolonged contact with foil can cause a minor chemical reaction that pits the foil's surface — this is a foil issue, not a basket one, and doesn't pose a safety risk, but can leave small foil fragments in food, so it's worth avoiding for very acidic, long-marinated dishes.