AltoPaint, a new painting app for iPhone Duo, iPhone and iPad, is live on the App Store today. It turns the screen into a pocket paint tin, with a small canvas in the lid, twelve pigments in the base and a mixing tray in between.
The app comes from High Line Labs, the New York studio founded by Instagram engineer Eric Kunz, and it launches on the same day as the iPhone Duo. It requires iOS 27 or iPadOS 27 and costs $4.99 during launch week, then $5.99. There are no subscriptions, in-app purchases or ads, and you can download it from the AltoPaint App Store page.
AltoPaint mixes twelve real pigments the way paint mixes
Each pixel on the canvas keeps track of how much of every pigment it holds, so colors blend like physical paint instead of sliding between two RGB values. Lemon and phthalo make green, cadmium yellow and red make orange, and ultramarine and magenta make violet. You mix by dragging the brush through two pigments, or by working them together on the tray.
The brush holds only so much paint, and strokes turn drier and streakier as it empties until a single dip breaks into scratchy dry-brush marks. You dip again to keep going, or tap the drop button to clean the brush before switching colors.
Wet paint drags. A lemon stroke across wet blue turns green, while a white stroke across blue that has already dried stays clean. Thick paint also catches the light, with visible bristle grooves, ridges and the mark where the brush stopped.
Oil, gouache and a palette knife come with no undo button
AltoPaint has no undo, so you paint over a mistake, scrape it back with the palette knife, or let it dry and work on top, and every error becomes part of the painting.
Oil stays glossy and wet for a while, which lets strokes drag into the paint beneath them. Gouache is matte and dries within a few strokes, so colors sit side by side. A clean palette knife smears one color into the next, while a loaded knife lays down flat, solid planes. The flat brush swells and thins like a pen nib as you turn the stroke.
Apple Pencil reads pressure, tilt and azimuth. Pressing harder gives a heavier stroke, and tilting paints with the side of the brush. Double-tapping the Pencil switches to the rag or back to your last brush, depending on your Pencil settings. Apple Pencil support was already working on iPhone Duo in iOS 27.2, so the foldable is covered from day one.
The tin opens along the iPhone Duo fold
The lid canvas sits on the top half of the screen and the pigments and tray lie flat on the bottom half, right where the iPhone Duo folds. Half-open, the phone holds the canvas up like the lid of a real tin. The iPhone Duo is also launching today, and early reviews call it the best foldable yet.
On any iPhone or iPad, the tin fills the screen instead. One finger always paints, a two-finger pinch zooms, and a two-finger drag moves around the canvas. AltoPaint saves as you paint, keeps every piece in a gallery, and shares finished work as an image through the share sheet.
The app collects no data and is available in English, Chinese (Simplified and Traditional), French, German, Italian, Japanese, Korean, Portuguese (Brazil), Russian and Spanish.
