Yes, in most air fryers. Keep it away from the heating element and don't let it block airflow around the food.
Foil in an oven is uncomplicated, but an air fryer's compact size and fan-driven heat change the calculus a little. The basket sits closer to the heating element than a full-size oven rack does, and airflow around the food is the whole point of the appliance.
Most air fryer manufacturers say foil is fine in moderation — it's specific placements and specific foods that cause the real problems.
A small sheet of foil under fatty or drippy food, like wings, bacon, or sausages, can make cleanup easier and catch grease before it smokes on the heating element below. Foil also works as a makeshift sling for lifting delicate food out of a deep basket without it falling apart. Weigh it down with the food itself, or crimp the edges so it can't flap around in the airflow once the fan kicks in.
Lining the entire basket with foil blocks the hot air that's supposed to circulate underneath and around the food, which defeats the point of an air fryer and can lead to uneven cooking, soggy spots, longer cook times, and in some models, heat building up in ways the appliance isn't designed for. Leave the perforated basket bottom exposed where possible, and use foil only under or around part of the food, not as a full liner.
Tomato-based sauces, citrus marinades, and vinegar-heavy dishes can react with aluminum, causing the foil to pit and small amounts of aluminum to migrate into the food — more of a taste and quality issue than a major health risk, but worth avoiding for flavor's sake. Use a parchment liner or the bare basket for those dishes instead.
Check your air fryer's manual, since a few compact or toaster-oven-style models have the heating element close enough to the basket that manufacturers advise against foil entirely. In general, foil that stays flat in the basket, is weighed down by food, and doesn't touch the top coil is fine across most standard basket-style air fryers. When you're unsure, the manual — or the manufacturer's FAQ page — settles it for your specific model; never test with loose foil in an empty basket, since unweighted foil is exactly what the fan can pull into the coil. Most standard models handle a small, secured sheet of foil without any issue at all, which is why the placement matters more than the material itself, and why blanket never-use-foil advice online is more cautious than most manufacturers actually require.
Foil isn't off-limits in an air fryer, but it needs to stay out of the way of the fan and the coil. Use it for drippy foods, skip it for acidic sauces, and never let it cover the whole basket.
Rarely, if it's placed correctly and doesn't touch the heating element. Loose foil pulled into the coil, or a fully lined basket blocking airflow, is what can cause scorching or uneven heating over time.
Neither is universally better — foil handles fatty, drippy foods well and conducts heat, while parchment is better for delicate or acidic foods since it doesn't react with them.
Most standard basket-style air fryers allow it, but some compact or toaster-oven-style models have the heating element closer to the food, so check the manufacturer's manual first.
It can, since foil blocks some hot air circulation around whatever it covers. Food under or wrapped in foil may need a few extra minutes compared to food cooked directly in the basket.