OpenStreetMap Nominatim — Free Geocoding API (No Key, Global)

TL;DR

Nominatim (from Latin "by name") is the official geocoding service for OpenStreetMap data. It converts free-text location queries into precise GPS coordinates (forward geocoding) and reverse-geocodes coordinates back into structured addresses. It covers the entire planet using OSM's community-maintained map data. The API requires a User-Agent header identifying your application and enforces a strict 1 request per second rate limit.

Quick start: https://nominatim.openstreetmap.org/search?q=New+York&format=json

No API key needed — just make a request!

How to Use This API

1. Forward Geocoding — Address to Coordinates

https://nominatim.openstreetmap.org/search?q=New+York&format=json

2. Reverse Geocoding — Coordinates to Address

https://nominatim.openstreetmap.org/reverse?lat=40.748817&lon=-73.985428&format=json

3. Structured Query

https://nominatim.openstreetmap.org/search?city=Tokyo&country=Japan&format=json

4. JavaScript — Geocode Search

fetch('https://nominatim.openstreetmap.org/search?q=Paris&format=json&limit=3', {
    headers: {'User-Agent': 'MyApp/1.0'}
  })
  .then(r => r.json())
  .then(results => {
    results.forEach(p => {
      console.log(p.display_name, '—', p.lat, p.lon);
    });
  });

5. Python — Lookup Address

import requests

headers = {'User-Agent': 'MyGeocoder/1.0'}
params = {'q': 'Statue of Liberty', 'format': 'json', 'limit': 1}

resp = requests.get('https://nominatim.openstreetmap.org/search',
                    params=params, headers=headers)
data = resp.json()[0]
print(data['display_name'])
print(f"Lat: {data['lat']}, Lon: {data['lon']}")
print(f"Type: {data['type']}")

Try it: https://nominatim.openstreetmap.org/search?q=London&format=json&limit=1

Try This URL Now

API Details

API URL: https://nominatim.openstreetmap.org
Documentation: nominatim.org
Category: Utility
Authentication: Not Required
Geographic Coverage: Global

Frequently Asked Questions

Do I need an API key?: No, but you must provide a User-Agent header identifying your application. Requests without one may be blocked.
What is the rate limit?: Maximum 1 request per second. For higher volume, you need to run your own Nominatim server using OpenStreetMap data exports.
What output formats are supported?: format=json (standard), format=jsonv2 (extended), format=xml, and format=html. JSONv2 includes additional address breakdown fields.
Can I restrict results to a specific country?: Yes, add &countrycodes=US to limit results to a specific country using ISO 3166-1 alpha-2 codes. Use comma separation for multiple countries.
What does the reverse geocoding response include?: It returns display_name (full address), address (structured breakdown: road, city, state, postcode, country), lat, lon, and OSM metadata.
How does the search score work?: Results include a importance score (0-1) based on OSM data quality and population. Higher importance results typically appear first.

What You Can Build

Address autocomplete for checkout forms
Map marker placement from address input
Reverse geocoding for clickable maps
Location-based search with coordinate boundaries
Delivery route planner with address validation