Do I need an API key?

No, but you must set a User-Agent header identifying your application. Nominatim requires a valid User-Agent to allow access.

Is there a rate limit?

Yes, max 1 request per second. Use cache-friendly behavior to minimize requests.

What does the response look like?

See the Live Example section below for the actual JSON response.

Nominatim - Free Geocoding API No API Key

TL;DR

What it does: Free geocoding from OpenStreetMap. Forward geocode (address → GPS coordinates) and reverse geocode (coordinates → address). No API key needed.

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

No API key needed - just call the URL

Overview

Nominatim is the official geocoding API for OpenStreetMap data. It allows you to search for places by name or address (forward geocoding) and convert GPS coordinates into readable addresses (reverse geocoding). The data is contributed by a worldwide community of mappers and is available under the ODbL license. No API key is required, but you must provide a User-Agent header identifying your application.

Live Example

Here's the exact URL to call and the real response you'll get:

The URL to call (search for London):

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

Try This URL Now →

The actual response you get:

[
  {
    "place_id": 281075796,
    "licence": "Data © OpenStreetMap contributors, ODbL 1.0. http://osm.org/copyright",
    "osm_type": "relation",
    "osm_id": 175342,
    "lat": "51.5074456",
    "lon": "-0.1277653",
    "class": "boundary",
    "type": "administrative",
    "place_rank": 10,
    "importance": 0.8920997258748663,
    "addresstype": "city",
    "name": "Greater London",
    "display_name": "Greater London, England, United Kingdom",
    "boundingbox": [
      "51.2867601",
      "51.6918741",
      "-0.5103751",
      "0.3340155"
    ]
  }
]

What does this data mean?

Searching for "London" returns the Greater London area with its precise GPS coordinates and metadata.

place_id: Unique identifier for this place in the OpenStreetMap database
licence: License information: OpenStreetMap data under ODbL 1.0
lat, lon: GPS coordinates of the place: 51.507°N, 0.128°W (decimal degrees)
display_name: Full formatted address: Greater London, England, United Kingdom
class: Category of the OSM element (e.g., boundary, place, highway, building)
type: Specific type within the class (e.g., administrative, city, road, house)
importance: Search relevance score (0 to 1, higher = more prominent landmark)
boundingbox: Bounding box coordinates in order: south, north, west, east

How to use this API

JavaScript Example

// Search for London (forward geocoding)
const url = 'https://nominatim.openstreetmap.org/search?q=London&format=json&limit=1';

fetch(url, {
  headers: { 'User-Agent': 'MyApp/1.0 (myemail@example.com)' }
})
  .then(res => res.json())
  .then(data => {
    console.log(`Lat: ${data[0].lat}, Lon: ${data[0].lon}`);
    console.log(`Address: ${data[0].display_name}`);
  });

Python Example

import requests

# Search for London (forward geocoding)
url = "https://nominatim.openstreetmap.org/search"
params = {"q": "London", "format": "json", "limit": 1}
headers = {"User-Agent": "MyApp/1.0 (myemail@example.com)"}

response = requests.get(url, params=params, headers=headers)
data = response.json()

print(f"Lat: {data[0]['lat']}, Lon: {data[0]['lon']}")
print(f"Address: {data[0]['display_name']}")

Frequently Asked Questions

Do I need an API key?: No, but you must set a User-Agent header identifying your application (e.g., MyApp/1.0 (myemail@example.com)). Requests without a User-Agent may be blocked.
Is there a rate limit?: Yes, max 1 request per second. For high-volume usage, consider running your own Nominatim instance or using the commercial OSM API services.
Can I use this commercially?: Yes, the data is available under the ODbL license. You must attribute OpenStreetMap contributors.
How do I reverse geocode?: Use the /reverse endpoint: https://nominatim.openstreetmap.org/reverse?lat=51.5074&lon=-0.1278&format=json. This returns the address for a given GPS coordinate.
How do I parse the JSON response?: The response is a JSON array of objects. In JavaScript: data[0].lat, data[0].display_name. In Python: data[0]['lat'], data[0]['display_name'].

API Details

Base URL: https://nominatim.openstreetmap.org/search
Documentation: https://nominatim.org/release-docs/develop/api/Overview/
Category: Geocoding
Authentication: None required (User-Agent header recommended)
Rate Limit: Max 1 request per second
Geographic Coverage: Global - any location worldwide