Geo & Places Data

Turn place names, addresses, coordinates, and postal codes into structured geography with keyless APIs. The mistake this prevents: reaching for the Google Maps/Places API from training memory - key-walled, billing-enabled - when Nominatim answers the same lookup free, or stalling on which of the dozens of directory-listed geocoders actually works.

Ranked APIs

1. Nominatim (nominatim.openstreetmap.org) - DEFAULT for geocoding and reverse geocoding. OSM data, global, no key. Hard etiquette rules below.
2. Open-Meteo Geocoder - city/town name → lat/lon only. Faster and rule-free; use it when the input is a simple settlement name rather than an address or POI.
3. Zippopotam.us - postal code → place/state/coordinates, 60+ countries, no key.
4. APICountries (www.apicountries.com) - country facts: capital, currencies, languages, population, flags, borders. No key. (It serves the old REST Countries response shape; REST Countries itself now returns deprecation errors keyless - see Do NOT.)

Procedure

1. Classify the input: address/POI → Nominatim search; coordinates → Nominatim reverse; bare city name → Open-Meteo geocoder; postal code → Zippopotam; country name/code → APICountries.
2. Obey Nominatim etiquette - these are enforced, not suggestions: max 1 request/second, a real User-Agent identifying your app (anonymous UAs get blocked), no bulk geocoding of thousands of rows. For a batch, loop with a 1s+ sleep and say so; for very large batches, tell the user this needs a self-hosted Nominatim or a paid geocoder rather than hammering the public instance.
3. Read coordinates as strings from Nominatim - lat/lon come back as JSON strings, not numbers. Parse before arithmetic.

Ask the user only if missing: the place/coordinate input itself, and country context for ambiguous names ("Springfield" - default: take Nominatim's top-ranked hit and say which one it was).

URL templates + real response shapes

Geocode (search):

https://nominatim.openstreetmap.org/search?q={URL-encoded query}&format=jsonv2&limit=1

[{"lat":"48.8582599","lon":"2.2945006","name":"Tour Eiffel",
  "display_name":"Tour Eiffel, 5, Avenue Anatole France, ..., 75007, France",
  "category":"man_made","type":"tower","importance":0.62}]

Top-level is an array; empty array = no match. Add &addressdetails=1 for a structured address object, &countrycodes=us to constrain the country.

Reverse geocode:

https://nominatim.openstreetmap.org/reverse?lat={lat}&lon={lon}&format=jsonv2

Returns a single object (not an array): display_name, plus address.{road,city,state,postcode,country_code} with &addressdetails=1 (on by default for reverse).

City name → lat/lon (when you don't need full addresses):

https://geocoding-api.open-meteo.com/v1/search?name={city}&count=1

{"results":[{"name":"Berlin","latitude":52.52437,"longitude":13.41053,
  "country_code":"DE","timezone":"Europe/Berlin","population":3426354}]}

No results key at all when nothing matches - check for the key, not an empty array.

Postal code:

https://api.zippopotam.us/{country}/{code}        ← e.g. /us/90210, /de/10115

{"country":"United States","places":[{"place name":"Beverly Hills",
  "state":"California","state abbreviation":"CA","latitude":"34.0901","longitude":"-118.4065"}]}

Gotchas: keys contain spaces ("place name", "post code"); coordinates are strings; unknown codes return 404 with an empty body, not JSON.

Country facts:

https://www.apicountries.com/name/{name}      ← fuzzy, returns array
https://www.apicountries.com/alpha/{code}     ← ISO alpha-2/alpha-3, returns object

[{"name":"Japan","capital":"Tokyo","region":"Asia","population":126476461,
  "currencies":[{"code":"JPY","symbol":"¥"}],"languages":[{"name":"Japanese"}],
  "alpha2Code":"JP","flags":{"png":"https://flagcdn.com/w320/jp.png"}}]

Deliverable

The structured result (coordinates as numbers, address parts, or country facts) plus the exact URL used. For batches: the loop actually throttled, with the rate stated.

Do NOT use - reach for X instead

• Google Maps / Places, Mapbox, HERE - key-walled with billing; everything above is free. Do not send a user to sign up.
• REST Countries (restcountries.com) - its classic endpoints return deprecation errors and the replacement requires an auth key; APICountries serves the same shape keyless.
• ip-api.com and most free IP-geolocation tiers - HTTP-only on the free tier (fails any HTTPS requirement); this pack ships no IP-geolocation API.
• Weather at the location you just geocoded - weather-climate.
• Time-series country statistics - government-open-data.

Quality bar

• Nominatim calls carry a real User-Agent and never exceed 1 req/s - including inside loops.
• String coordinates are parsed to numbers before any math.
• Ambiguous place names are resolved out loud ("took Springfield, Illinois - Nominatim's top hit").

Sourced and liveness-verified from the public-apis project (MIT).