Made for iPhone Duo: These apps show what Apple’s foldable can do

Even before the iPhone Duo goes on sale, developers have already explored what Apple's foldable smartphone can do beyond conventional app interfaces. On September 26, Bitrig hosted the “Bitrig Hacks: iPhone Duo Edition” hackathon at Y Combinator's office in San Francisco. The event was supported by Y Combinator, OpenAI, RevenueCat, Sentry and Supabase, among others. Apple itself was neither an organizer nor an official sponsor, but provided the technical foundation with Xcode 27.1 Beta, the iOS 27.1 simulator and the new Duo APIs.

The goal: Participants weren't supposed to build ordinary apps that just happened to run on a foldable, but instead develop ideas that genuinely benefit from two displays, different folding angles and the hinge. However, they weren't required to create a market-ready app, only a working prototype. Since the iPhone Duo won't begin shipping until October 23, no retail devices were available yet. Bitrig therefore integrated its own interactive simulator, allowing developers to open, close and rotate the virtual device and test it at different angles.

An overview of the submitted projects was published on Devpost. Below, we take a look at some of the most interesting apps.

First place goes to MPC app that uses the hinge as a music control

First place went to Crate – an MPC app for the iPhone Duo created by Shuhan-Zhang Zhang, Aradhya Mishra and Mahin Bharathwaj. The AI-powered music sampler splits the controls across both halves of the device: The pads are located on the bottom display, while samples and additional information appear on the top. The real highlight, however, is the hinge: Audio effects can be controlled depending on the angle, with quickly opening the device triggering a musical drop, for example. The winners received an interview with Y Combinator, a $500 Apple gift card and $5,000 in OpenAI credits.

Second place for turning the iPhone Duo into a Walkman

Second place went to Duo-Man, an app created by Vidit Bhargava. It turns the iPhone Duo into a kind of digital Walkman. When the device is open, users select an album or cassette, and closing it starts playback. To make the experience feel retro beyond just the visuals, the developer says he recorded real button and interference sounds from a Walkman and integrated them into the app. The second-place winner received $500 in Supabase credits and $2,500 in OpenAI credits.

Third place for beauty assistant with stand functionality

Third place went to the Saura app by Gergana Dragoeva Quievy and Prakash Acharya. Here, the half-open iPhone Duo serves as a self-standing beauty assistant. One half can be used as a mirror, while step-by-step instructions appear on the other display. The app is designed to recognize routines from videos and turn them into personalized skincare or beauty steps. The team behind the Saura app won $1,000 in OpenAI credits.

Special award goes to dual-display translator

The RevenueCat special award for “Best RevenueCat creation” went to TranslateCat by Vasanth Sreeram for his dual-display translation app. The idea is simple but fits the dual-display concept particularly well: Two people face each other and see the appropriate translation on the display facing them. The prototype supported 16 languages. The prize was an iPhone Duo.

From an accordion to a monster game: More unusual ideas

There were also plenty of creative concepts beyond the winners. Accorduon, for example, turns the iPhone Duo's hinge into the bellows of a virtual accordion, while Arden transforms the iPhone Duo into a small gaming console with a screen and virtual controls. In Foldtales, the folding angle is used to make characters and objects appear three-dimensional, similar to a traditional pop-up book.

One particularly unusual project is Monster, Ink., a playful focus app: As long as the iPhone Duo remains closed, a small pixel cat gradually builds a city. When the device is opened, two red cat eyes first appear as a warning. If the smartphone is unfolded completely, the cat awakens as a giant monster, destroys the city and ends the focus session. Devpost lists a total of 161 participants and 73 submitted projects. An overview of all projects is available here.