A hackathon app turns the iPhone Duo into a working Sony Walkman

Developer Vidit Bhargava built the app around the iPhone Duo's folding hinge, turning the physical act of opening and closing the phone into the same ritual as loading a cassette.

• Open the Duo: Pick and "insert" a virtual cassette.
• Close the Duo: Playback starts, just like snapping a real Walkman shut.
• Sound design: Real recorded button clicks and cassette static from an actual Walkman.

The catch: it started as nothing more than a fun demo. Bhargava has since decided to turn it into a real, released app rather than leaving it as a one-off hackathon project.

Bhargava created Duo-Man at a hackathon called bitrig hacks, and he came prepared for an audience who likely had never seen a Walkman in person.

In real life If you're old enough to remember loading a cassette into a Walkman before heading out the door, Duo-Man is built to recreate that exact muscle memory, down to the sound of the tape mechanism.

Bhargava brought an actual physical Sony Walkman to the hackathon specifically so attendees could see what the original device looked like, since many had likely never encountered one.

That detail says as much about the Walkman's place in tech history as the app itself. Before the Walkman existed, portable music meant heavy, bulky cassette players that weren't practical to actually carry around. Sony solved that by shrinking down a cassette recorder originally designed for journalists.

Why it matters: the original 1979 Sony Walkman TPS-L2 actually launched with two headphone jacks and an orange "hotline" talk button, labeled "guys" and "dolls," because Sony chairman Akio Morita believed it would be rude for one person to listen to music alone. Buyers ignored that idea almost immediately, and Sony quietly dropped both features within a few years as solo listening became the entire point.

That single-listener experience the Walkman accidentally created went on to define decades of personal audio, and the device itself sold more than 250 million units worldwide over its lifetime. Duo-Man is recreating the tail end of that legacy on hardware Sony could never have imagined back in 1979, using a folding glass slab instead of a plastic cassette deck.

Bhargava didn't rely on generic beeps or stock audio for Duo-Man's interface. He recorded real button clicks and static directly from a working Walkman, according to his own account of the project.

By the numbers: that level of care, matching physical hinge gestures to specific real-world audio, is what separates a genuine recreation from a simple skinned music player app. It's a detail easy to skip but central to why the app resonated with people who remember the original device.

What began as something Bhargava built purely for fun at a hackathon is now becoming an actual released app. He's said Duo-Man will support Apple Music, meaning users will eventually be able to load real songs and playlists into the retro cassette interface rather than just simulating the experience with no real audio behind it.

That shift, from throwaway hackathon project to planned release, is a familiar path for small, charming apps that unexpectedly resonate once shared publicly. A video of the app in action drew attention on X after Bhargava posted it, helping push the idea beyond the hackathon room it started in.

Duo-Man's cassette-loading gesture only works because of specific choices Apple made with its first foldable phone. The iPhone Duo uses a book-style titanium design that opens like a small hardback, with a 7.6-inch inner OLED display and an A20 Pro chip.

What's next: the Duo is set to launch October 23, 2026, with preorders opening October 16, starting at $1,999 for the base 256GB model and climbing to $3,199 for the 2TB version. Notably, Apple skipped a telephoto lens and traditional Face ID on the Duo, using a Touch ID side button instead, tradeoffs made to accommodate the folding design.

That opening and closing motion, the exact gesture central to using a folding phone at all, happens to double perfectly as the cassette-insertion ritual Duo-Man is built around. It's the kind of coincidence that makes a hardware quirk feel purpose-built for an app nobody at Apple ever planned for.

Apple's own reasons for skipping a telephoto lens and Face ID were almost certainly about engineering tradeoffs and internal component space inside a folding chassis, not about leaving room for retro cassette apps. But the end result still gave an independent developer exactly the physical interaction a decades-old audio format needed to feel natural on a brand-new device.

Duo-Man isn't happening in isolation. It lands alongside a broader wave of retro-tech nostalgia this year, from wired earbuds making a comeback to renewed interest in older, simpler device designs generally.

By the numbers: design trend watchers have pointed to a rise in what's being called "skeuomorphism 2.0" throughout 2026, interfaces that deliberately recreate real-world textures and objects rather than staying flat and minimal. Spotify has its own cassette-tape-style playback interface as an example, and Instagram faced a genuine backlash after modernizing its app icon, eventually offering a paid option to unlock the older "throwback" version instead.

Apple's own iPhone Duo, a genuinely new hardware form factor, becoming the vehicle for recreating a nearly 50-year-old product category is a neat bit of full-circle design thinking, whether or not that was Bhargava's original intent when he sat down to build it.

Bhargava hasn't given a firm release date for Duo-Man's public launch, and the exact scope of the Apple Music integration remains unclear ahead of release. What is clear is that demand exists well beyond the room where it was built, given the amount of attention the project has already drawn online since the first video appeared.

Independent developer apps built around a single clever idea often face a choice once they attract this kind of attention: expand into something broader and lose the focused charm that made the original demo work, or stay narrow and risk feeling like a novelty that fades once the initial nostalgia wears off.

Duo-Man's planned Apple Music support suggests Bhargava is aiming for the former without abandoning the retro interface that makes the whole app distinctive in the first place.