I made a better county finder (opens in new tab)

(tyjkot.com)

2 pointstyjkot18d ago3 comments

3 comments

3 comments · 1 top-level

tyjkotOP18d ago· 2 in thread

If you've ever searched for a county finder, you've probably noticed that nearly all of them are loaded with ads. It becomes a race to use the search bar and get your result before the page turns into a digital labyrinth.

I made my own county finder. It's ad-free, and I think it's better than anything else out there.

I haven't tested all the edge cases yet, especially addresses that fall near county lines. However, for 95% of use cases, it's pretty badass if I do say so myself.

Let me know what you think, or if you have any suggestions.

gus_massa17d ago

Can you share any details of the tech stack? What maps are you using? Openstreetmap?

tyjkotOP17d ago

Yep! OpenStreetMap all the way down. Leaflet for the map with OSM raster tiles, and Nominatim for geocoding the typed address (US-restricted). County boundaries are US Census data as TopoJSON (~0.8 MB), self-hosted and decoded client-side with topojson-client. Once that loads, clicking the map resolves to a county with a local ray-casting point-in-polygon check - no API call. County lines and labels only render for what's in the viewport past a zoom threshold. React + Vite around it. No backend, no keys, no paid APIs.

For easy reading:

- Frontend: React 18 + Vite, React Router

- Map: Leaflet, lazy-loaded when the tool page mounts

- Base tiles: OpenStreetMap raster tiles (free, no key)

- Geocoding: Nominatim (US-restricted), only for typed address searches

- County boundaries: US Census TopoJSON (~0.8 MB), self-hosted, decoded client-side with topojson-client

- Click-to-county: local ray-casting point-in-polygon - no API call

- County lines/labels only render for the visible viewport past a zoom threshold

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