One Second

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  OneSecond-Screenshot

Inspiration

Our camera rolls have become digital attics.

We capture hundreds of photos and videos, but most of them disappear into an endless stream of screenshots, duplicates, random clips, and forgotten moments. Traditional journaling has the opposite problem: it asks people to write regularly and document their entire day.

I wanted something in between.

One Second started with a simple question:

What do you want to remember from today?

The idea is deliberately small. Instead of capturing everything, the user preserves one meaningful moment from each day.

What I Built

One Second is a minimalist visual journal for short daily memories.

The core experience lets users capture a brief visual moment, save one official memory for the day, and revisit their collection through a private library and calendar.

As the archive grows, those memories become monthly and yearly replays, turning small daily moments into a longer personal story.

The product intentionally has no social feed, likes, followers, or engagement metrics. It is designed for remembering, not performing.

ONE SECOND+

The premium experience, ONE SECOND+, adds features for people who want to keep their memories safer and revisit them over longer periods.

RevenueCat powers the subscription experience and handles the monetization flow.

For this student submission, the development build demonstrates the RevenueCat purchase experience using its Test Store environment.

How I Built It

This was my first hackathon and my first mobile application.

I built One Second with React Native and Expo using TypeScript, with Expo Router handling navigation and a local memory architecture powering the core experience.

I also built the daily official-memory system and the monthly and yearly replay system so that memories are not just stored, but given a structure for revisiting them later.

Challenges and What I Learned

One of the biggest challenges was deciding what not to build.

It was tempting to add social features, AI, more ways to capture memories, and increasingly complex functionality. Instead, I kept returning to the original idea and removed anything that distracted from it.

That process taught me that good product design is sometimes about reducing possibilities rather than adding them.

I also learned how different mobile development is from building a web project, particularly around device testing, Android builds, navigation, and subscription infrastructure.

Why One Second

You do not need to capture everything to remember what mattered.

One Second is built around that idea: one small moment, intentionally kept, every day.

Built With

• android
• expo.io
• exporouter
• reactnative
• revenuecat
• typescript