Preheat: Preheat your air fryer to 400°F (200°C). Preheating ensures the grapes start caramelizing immediately rather than slowly warming up.
Prep the grapes: Wash thoroughly and pat completely dry with paper towels. Remove from stems. Dry grapes caramelize better — excess moisture creates steam and prevents browning.
Season: Toss grapes in a bowl with olive oil and a pinch of sea salt. Mix gently to coat evenly. Add optional seasonings (cinnamon, chili flakes, rosemary) at this stage.
Arrange in basket: Place grapes in a single layer in the air fryer basket. Don't overlap — they need space for hot air to circulate. Work in batches for large quantities.
Air fry: Cook at 400°F for 10–12 minutes, shaking the basket once at the 5-minute mark. Check at 8 minutes — smaller grapes may be done early.
Check for doneness: Grapes are done when skins have split and darkened, grapes look blistered and slightly deflated, and juices may be bubbling. For more caramelization, add 2–3 more minutes.
Serve immediately: Air fryer grapes are best served warm, right after cooking. See the serving section below for the best ways to enjoy them.