Plany

Inspiration

Planning a trip with friends sounds fun - until you're 47 messages deep and still haven't picked a date.

We've all been there. Someone says "down!" Someone says "maybe." Someone goes silent for three days. The group chat becomes the trip's biggest obstacle, and half the time the trip just doesn't happen.

We built Planny because coordination is exhausting. What if one agent could handle the whole trip?

What it does

Planny is an AI trip planning tool for groups. You tell Planny where you want to go, who's coming, and the vibe you're after. Then Planny takes over.

Planny reaches out to everyone in your group on your behalf, collects their preferences and availability, and finds dates that actually work. No one has to do anything except respond to Planny. The finalized itinerary surfaces in the app.

No follow-ups. No scheduling threads. No one getting left behind.

How we built it

Planny is built on React + Vite frontend, Node.js / Express backend, and SQLite for local storage.

The core is a privacy-preserving agent negotiation loop powered by Claude (claude-sonnet-4-20250514). Two Claude instances coordinate on behalf of users via Maritime, an agent-to-agent pub/sub messaging layer, running up to 5 rounds of negotiation.

Scheduling uses real Google Calendar data via OAuth 2.0, and WebSockets stream live agent activity into the browser during active sessions.

Challenges we ran into

Integrating with messaging platforms was harder than expected. Some require approval processes that take days, which isn't compatible with a hackathon timeline. We had to find workarounds to demonstrate the core coordination flow without full native integrations.

Accomplishments that we're proud of

Built a working multi-party coordination flow in 3 hours
Real calendar data feeds directly into scheduling, no manual input needed
Designed a UX where the trip organizer does almost nothing after the initial prompt
Made scheduling feel effortless for everyone in the group, not just the person who initiated