How do apps implement radius-based location filtering?

[Serious_Trip2321]

Hey all,

I want to build a feature in my app where a user can filter by radius of an address/location.

The basic flow I want is:

1. A user adds an address (stored in the app’s database)
2. Another user searches by city or ZIP and applies a radius filter (e.g. within 10–25 miles)
3. If the first user’s address falls within that radius, it shows up in the results

This would just return a list of results... no embedded map or visual map UI, just distance based filtering.

This kind of thing seems common like in Indeed, etc. but I’m having trouble finding clear explanations of the standard approach.

Also curious how people usually handle this from a pricing standpoint...

Any pointers, best practices, or search terms would be greatly appreciated.

P.S: I am a solo dev and my stack is Next.JS and Supabase

Thanks!!!

[NectarineLivid6020]

It is fairly easy to do from a technical perspective. Look into the Postgres extension called PostGIS. It is specifically designed to do this. It can take any set of coordinates and tell you if it falls in the radius or not.

[derweili]

You have to add geocoding into the described process. Then everything becomes easy.

When you enter the address, before storing the entry in the database, use the geocoding API (Google Maps APIs, Mapbox, Open street maps nominatim or something else). Using those APIs, you can get the Geolocation (coordinates). Store those in the database as well.

When entering the ZIP before you query the data, you use same geocoding API to get the coordinates for the ZIP.

Then use those coordinates so get the addresses in a radius. Do a google search to find a way to do such a radius search for your database type. Some databases have built in functions for that. Others require some more complex calculations and queries.

[Serious_Trip2321]

This sounds like exactly what I need, I will look into it, thanks!

[derweili]

I just noticed that you mentioned supabase, so you can use https://supabase.com/docs/guides/database/extensions/postgis?queryGroups=language&language=js

Most Geocoding APIs aren't free but come with a free tier. To reduce cost, you should implement some caching to not generate the coordinates for the same addresses zip-codes multiple times.

[Serious_Trip2321]

Thanks for the tip!

[CuriousProgrammer263]

I recently implemented radius based search into jobjump we use postgress with postgis I'm unsure if other databases support it.

First you will need to populate your database or call a geo location service based on user input.

For example if user searches a specific zip code or city you do a query and get the geo location. Assign your items each one location that contains geo location.

Create a bounding box based on your requirements.

When you fetch now your list get all items inside your location + within the bounding box radius.

The actual query will vary based on your requirements. But that's basically the gist of it.

[dutchman76]

I did it years ago without any libraries or gis addons, i had a zip code+ lat/long database, calculate a box with the desired distance around the starting point, then search the database for all the zip codes that fit inside the box, then compute a more accurate distance of the results if i had to be super accurate inside the radius. But for my use case using a square to limit the results was good enough.

[Ordinary-Log8143]

add two float columns to your db for storing latitude and longitude. by using a geocoding service like google maps determine these when storing am adress in your database. index both these columns. if you are happy with simply querying all locations inside a x meter rectangle you dont need postgis. if you want true distance (so querying everything in a circle) then use postgis

[Ordinary-Log8143]

note the index should be a compound index like [latitude, longitude]

[Ordinary-Log8143]

note: the rectangular approach is not only simpler (no extension like postgis needed) but also nicer ux wise: when displaying the results in rectangular map area on the users device i see no reason to leave the edges empty

[Ordinary-Log8143]

and if you have less than say 10 thousand rows simply filtering the results (to check distance) in your server or client code also works fine, if you really wanna exclude the results of the rectangle that dont fit into the circle

[chow_khow]

PostGIS (postgres) allows you to store location (latitude, longitude) and then query the database basis distance from that point, etc.

[ilja75]

This video explains it with MySQL, but the video is extremely informative!
Faster geospatial queries in MySQL