Imagine a camera that deliberately doesn't show you the photo right away. You take a shot, and you only see it 24 hours later — exactly like waiting for film to be developed at a photo shop. That's Flashback: a physical camera with a 27-shot roll (exactly like a film cartridge) plus an app that holds the suspense for a full day. The product hit the nostalgia for analog photography so precisely that even FC Barcelona's women's team uses it in their content.We joined Flashback when the app was already live in the App Store. The brief sounded simple: "get the product in shape and keep growing it." In practice, that hid several engineering puzzles that directly determined whether the product could even keep its core promise.
A camera that didn't always listen
The first thing we ran into: the device's camera integration behaved unpredictably. Shooting, filters, saving a frame — all of it was supposed to work the same way regardless of the phone or the situation. But part of the scenarios broke: sometimes a frame wouldn't save, sometimes a filter applied incorrectly. For an app whose entire function is to take a photo and not lose it, that's critical. We rebuilt the interaction with the Camera API, closing edge cases one by one until the core flow worked reliably every time.
The product's main feature sat on fragile synchronization
The 24-hour delay isn't a side effect — it's the entire point of Flashback. And that's exactly where the weakest point was: the state of "when a frame can be opened" didn't always sync cleanly between the app and Firebase. A photo could appear too early, too late, or get lost in the process entirely. We made sure the reveal timer was reliably tied to Firebase, so a frame becomes visible exactly when promised — no exceptions, no manual intervention from developers.
Weaker phones couldn't handle large photos
Original-quality photos are heavy files. Everything ran smoothly on flagship phones, but on weaker devices the app started lagging exactly at the moment of shooting or uploading — precisely where users expect speed the most. We optimized media processing across the entire pipeline, from camera to gallery, so speed no longer depended on which phone you had.
Bad connectivity had no right to cost you a frame
The last challenge was unstable internet. In most apps, a lost request is a minor inconvenience — you retry and move on. But in Flashback, every frame is unique and has been waiting for you for a full day — losing it to a dropped connection would undermine trust in the entire product. We made Firebase sync resilient to interruptions, so no frame and no upload status gets lost, even when the network misbehaves.
What came out of it
An app that used to fail in some scenarios now keeps its core promise without exception: the frame appears exactly 24 hours later, no file gets lost, and speed doesn't depend on the phone model. And it seems to be working — because a product that started as a tool for analog photography enthusiasts is now on camera with FC Barcelona Femení.For us, it's a reminder of why "small" technical details — a timer, state synchronization, media processing — are actually the product. The user doesn't see Firebase or the Camera API. They only see whether the camera kept its promise.