Echoes

Home page for nearby echoes
Adding a new echo (private/public)
Profile page with social features

Inspiration

Echoes was inspired by the idea that places should be able to hold memories. Social media today disconnects stories from where they actually happened, so we wanted to build something that turns the real world into a persistent social canvas. Instead of scrolling from your couch, you explore on foot and discover messages, memories, and moments left at real locations around you.

What it does

Echoes lets users leave short text messages anchored to physical locations and discover them later in AR. Users can view nearby Echoes on a radar-style map, then lift their phone to switch into AR and see messages placed around them. Echoes supports cross-user persistence, public or friends-only visibility, reporting, and location-aware rendering with geofenced discovery.

How we built it

We built Echoes as a React Native mobile app with Expo, using ViroReact for AR experiences across ARKit and ARCore. Supabase handled authentication, PostgreSQL storage, PostGIS spatial queries, and backend logic. For positioning, we designed a hybrid anchoring system that uses geospatial anchors, cloud anchors, and GPS fallback so Echoes can stay tied to real spaces as accurately as possible.

Challenges we ran into

Our biggest challenge was spatial accuracy. GPS alone is not precise enough for a magical AR experience, especially indoors, so we had to design a tiered anchoring strategy. We also had to deal with AR testing constraints, since AR features require physical devices instead of emulators, and cross-user anchor resolution can fail if the environment changes or positioning data is weak.

Accomplishments that we're proud of

We are proud of turning a big vision into a focused MVP with a strong core loop: discover nearby Echoes, lift into AR, and view messages anchored to the world around you. We are especially proud of the Lift-to-AR interaction, the cross-platform architecture, and the hybrid anchoring system that makes Echoes feel more precise and immersive than a simple GPS-based demo.

What we learned

We learned that building AR products is as much about system design and fallback logic as visual polish. Precision, persistence, and device constraints matter a lot more than they seem at first. We also learned the value of simplifying scope: by keeping the MVP text-only and using Supabase as a full backend platform, we reduced complexity and focused on making the core experience actually work.

What's next for Echoes

Next, we want to polish the app, improve anchor reliability, and expand beyond the MVP. That includes richer social features, stronger moderation, better AR realism, and eventually support for media Echoes, group-based experiences, and multi-campus rollout. Long term, we see Echoes growing from a campus product into a new kind of location-based social platform for cities, events, and public spaces.

I can also make these sound more hackathon-y, more technical, or more emotional depending on the vibe you want for Devpost.