CityX

Inspiration

Inspiration

Investing is social, but today it happens in anonymous feeds, while the city you live in is full of the companies you hold. We wanted to put finance back on the map: the office down the street, the people nearby who hold the same stock, and a way to meet them that respects privacy.

What it does

• A living map of New York: 47 NYC-headquartered public companies, startups that are raising, and people nearby. Rings show a wealth tier, never an amount, and every owner controls who can see their card.
• Filings in plain words: revenue, profit and cash from SEC filings ("keeps 4¢ of every $1 of sales"), fiscal periods and filing currencies labelled, and every number traceable to its source filing. A Pro mode adds valuation multiples, an LBO sandbox with sliders, and a working-paper export.
• Ask in plain language: "compare DDOG and MDB P/E". The numbers are computed by code from filings; the text only explains them.
• Stock circles: holder-only community feeds with a public preview. Members choose whether each post is for the circle or for everyone.
• Consent-first social: you start by sending your profile, and chat opens only when the other person accepts. Meetups need two yeses (the meeting, then the restaurant), with fair meeting-point suggestions from OpenStreetMap.
• Paper trading and community sentiment: simulated orders, bull/bear votes with sample sizes and k-anonymity, and theses tracked against the S&P 500. No copy-trading, and no leaderboards ranked by returns.

How we built it

React + TypeScript + Vite with MapLibre GL (3D map, day/night themes) on the frontend; Python FastAPI on the backend. Data comes from SEC EDGAR XBRL filings and OpenStreetMap, plus a pluggable market-data layer (a demo source today, with an adapter ready for a licensed provider). Privacy is enforced on the server: k-anonymous counts, owner-controlled disclosure and consent gates. The app has an offline "airplane mode" for live demos, and 900+ automated tests.

Challenges we ran into

• Making financial data trustworthy: fiscal vs. calendar quarters, non-USD filers, and filing dates that shift across time zones.
• Designing social features that feel exciting without nudging people to trade. That is why we removed copy-trading and replaced it with transparent, paper-tracked theses.
• Stopping privacy leaks through side channels: counts, notifications and what happens after someone sells their position.

Accomplishments that we're proud of

A single connected journey from company to filing to people to meeting, where every number has a source and every connection has consent.

What we learned

Trust is a feature: plain-language explanations, visible data sources and consent at every step matter as much as the data itself.

What's next for CITYX

Licensed real-time market data, verification with real brokers, more cities, and community tools around shared interests.

Built With

• fastapi
• maplibre-gl
• openfreemap
• openstreetmap
• overpass-api
• python
• react
• sec-edgar
• typescript
• vite
• websockets-sse
• xbrl