PopBy

Inspiration

The best parts of a city are often tiny: a tree glowing at sunset, a song through an open window, or a thought tied to a street corner. PopBy is for people who want a quiet sense of company without physical interaction. You can unlock other's feeling when popping by the same place, then drop something for the next person. No profiles, likes, followers, or social pressure.

What it does

PopBy turns a neighbourhood into a map of location-based Thoughts. Walk within 50 metres to unlock a note, photo, or even music, then long-press nearby to pop your own. Mine layer reveals your own personal city memories.

How we built it

We built PopBy as a mobile web app using React, Vite, Mapbox Standard 3D, Turf.js, Supabase, PostGIS, and Vercel. An anonymous device ID manages Mine, unlock history, reports, and rate limits. Before publishing, PopBy checks for buildings, moves the drop to a safer public path, and stores only that safe location. It does not save any raw GPS or long-press coordinates.

Challenges we ran into

Maps become complicated fast on a phone. We had to separate a long-press from a pan, keep markers attached during 3D zoom, handle Android touch behaviour, and stop cards from fighting map gestures. Our biggest challenge was keeping the magic of location-based discovery while protecting where users actually stood.

Accomplishments that we're proud of

The PopBy main function works well: explore, approach, unlock, read, create, and return through Mine. Our animated tutorial visually demonstrates this loop inside the real interface. We also built diversified Thought cards, live-camera backgrounds, BGM links, privacy anchoring, reporting.

What we learned

We released there are so many small details we need to decide in a location product, for example, a drifting marker, crowded mobile text, or confusing distance rule can change the whole experience. Building the tutorial around real interactions also brings much more problems than a normal onboarding slideshow.

What's next for

We want to open more Melbourne suburbs, strengthen upload moderation, and test PopBy through real neighbourhood walks. Our business model will keep the experience calm and free from intrusive advertising:

Personal Memory Plus: paid themes, fonts, private collections, yearly recaps, and memories exported as postcards or books.
Local Nooks: independent shops can share a hidden story and a gentle reward that unlocks when someone visits, turning PopBy into measurable foot traffic.
Sponsored cultural trails: thoughtful brands could support experiences such as quiet city walks, or location-based sound journeys.

React to the feedback from our mentor

The mentor suggested that we open one suburb first, start small to observe how it works and gather feedback, and build a plan to unlock more suburbs month by month. We chose Fitzroy as our first suburb which is most relevant to our target users. We adopt a strategy that visualises the unlocking progress of subsequent locations to motivate users to get involved in the build-out progress.