Developer Guide

Introduction

The Geolocation API returns a location and accuracy radius based on information about cell towers and WiFi nodes that the mobile client can detect. This document describes the protocol used to send this data to the server and to return a response to the client.

Communication is done over HTTPS using POST. Both request and response are formatted as JSON, and the content type of both is application/json.

Before you begin

Before you start developing with the Geolocation API, review the authentication requirements (you need an API key) and the API usage and billing information (you need to enable billing on your project).

Geolocation requests

Geolocation requests are sent using POST to the following URL:

https://www.googleapis.com/geolocation/v1/geolocate?key=YOUR_API_KEY

You must specify a key in your request, included as the value of a key parameter. A key is your application's API key. This key identifies your application for purposes of quota management. Learn how to get a key.

Request body

The request body must be formatted as JSON. The following fields are supported, and all fields are optional:

homeMobileCountryCode: The mobile country code (MCC) for the device's home network.
homeMobileNetworkCode: The mobile network code (MNC) for the device's home network.
radioType: The mobile radio type. Supported values are lte, gsm, cdma, and wcdma. While this field is optional, it should be included if a value is available, for more accurate results.
carrier: The carrier name.
considerIp: Specifies whether to fall back to IP geolocation if wifi and cell tower signals are not available. Defaults to true. Set considerIp to false to disable fall back.
cellTowers: An array of cell tower objects. See the Cell Tower Objects section below.
wifiAccessPoints: An array of WiFi access point objects. See the WiFi Access Point Objects section below.

{
  "homeMobileCountryCode": 310,
  "homeMobileNetworkCode": 410,
  "radioType": "gsm",
  "carrier": "Vodafone",
  "considerIp": "true",
  "cellTowers": [
    // See the Cell Tower Objects section below.
  ],
  "wifiAccessPoints": [
    // See the WiFi Access Point Objects section below.
  ]
}

Cell tower objects

The request body's cellTowers array contains zero or more cell tower objects.

cellId (required): Unique identifier of the cell. On GSM, this is the Cell ID (CID); CDMA networks use the Base Station ID (BID). WCDMA networks use the UTRAN/GERAN Cell Identity (UC-Id), which is a 32-bit value concatenating the Radio Network Controller (RNC) and Cell ID. Specifying only the 16-bit Cell ID value in WCDMA networks may return inaccurate results.
locationAreaCode (required): The Location Area Code (LAC) for GSM and WCDMA networks. The Network ID (NID) for CDMA networks.
mobileCountryCode (required): The cell tower's Mobile Country Code (MCC).
mobileNetworkCode (required): The cell tower's Mobile Network Code. This is the MNC for GSM and WCDMA; CDMA uses the System ID (SID).

The following optional fields are not currently used, but may be included if values are available.

age: The number of milliseconds since this cell was primary. If age is 0, the cellId represents a current measurement.
signalStrength: Radio signal strength measured in dBm.
timingAdvance: The timing advance value.

An example GSM cell tower object is below.

{
  "cellTowers": [
    {
      "cellId": 42,
      "locationAreaCode": 415,
      "mobileCountryCode": 310,
      "mobileNetworkCode": 410,
      "age": 0,
      "signalStrength": -60,
      "timingAdvance": 15
    }
  ]
}

An example WCDMA cell tower object is below.

{
  "cellTowers": [
    {
      "cellId": 21532831,
      "locationAreaCode": 2862,
      "mobileCountryCode": 214,
      "mobileNetworkCode": 7
    }
  ]
}

WiFi access point objects

The request body's wifiAccessPoints array must contain two or more WiFi access point objects. macAddress is required; all other fields are optional.

macAddress: (required) The MAC address of the WiFi node. It's typically called a BSS, BSSID or MAC address. Separators must be : (colon).
signalStrength: The current signal strength measured in dBm.
age: The number of milliseconds since this access point was detected.
channel: The channel over which the client is communicating with the access point.
signalToNoiseRatio: The current signal to noise ratio measured in dB.

An example WiFi access point object is shown below.

{
  "macAddress": "00:25:9c:cf:1c:ac",
  "signalStrength": -43,
  "age": 0,
  "channel": 11,
  "signalToNoiseRatio": 0
}

Geolocation responses

A successful geolocation request will return a JSON-formatted response defining a location and radius.

location: The user’s estimated latitude and longitude, in degrees. Contains one lat and one lng subfield.
accuracy: The accuracy of the estimated location, in meters. This represents the radius of a circle around the given location.

{
  "location": {
    "lat": 51.0,
    "lng": -0.1
  },
  "accuracy": 1200.4
}

Errors

In the case of an error, a standard format error response body will be returned and the HTTP status code will be set to an error status.

The response contains an object with a single error object with the following keys:

code: This is the same as the HTTP status of the response.
message: A short description of the error.
errors: A list of errors which occurred. Each error contains an identifier for the type of error (the reason) and a short description (the message).

For example, sending invalid JSON will return the following error:

{
 "error": {
  "errors": [
   {
    "domain": "global",
    "reason": "parseError",
    "message": "Parse Error",
   }
  ],
  "code": 400,
  "message": "Parse Error"
 }
}

Possible errors include:

Reason	Domain	HTTP Status Code	Description
`dailyLimitExceeded`	`usageLimits`	403	You have exceeded your daily limit.
`keyInvalid`	`usageLimits`	400	Your API key is not valid for the Geolocation API. Please ensure that you've included the entire key, and that you've either purchased the API or have enabled billing and activated the API to obtain the free quota.
`userRateLimitExceeded`	`usageLimits`	403	You have exceeded the requests per second per user limit that you configured in the Google Cloud Platform Console. This limit should be configured to prevent a single or small group of users from exhausting your daily quota, while still allowing reasonable access to all users.
`notFound`	`geolocation`	404	The request was valid, but no results were returned.
`parseError`	`global`	400	The request body is not valid JSON. Refer to the Request Body section for details on each field.

Sample requests

If you'd like to try the Geolocation API with sample data, save the following JSON to a file:

{
  "considerIp": "false",
  "wifiAccessPoints": [
    {
        "macAddress": "00:25:9c:cf:1c:ac",
        "signalStrength": -43,
        "signalToNoiseRatio": 0
    },
    {
        "macAddress": "00:25:9c:cf:1c:ad",
        "signalStrength": -55,
        "signalToNoiseRatio": 0
    }
  ]
}

You can then use cURL to make your request from the command line:

$ curl -d @your_filename.json -H "Content-Type: application/json" -i "https://www.googleapis.com/geolocation/v1/geolocate?key=YOUR_API_KEY"

The response for the above Mac addresses looks like this:

{
  "location": {
    "lat": 33.3632256,
    "lng": -117.0874871
  },
  "accuracy": 20
}

(See Get a Key if you don't have an API key.)

For additional testing, you can gather information from your Android device using the Places SDK for Android and the Android Location APIs, and from your iOS device using the Places SDK for iOS.

Frequently asked questions

Why am I getting a very large accuracy radius in my Geolocation response?

If your Geolocation response shows a very high value in the accuracy field, the service may be geolocating based on the request IP, instead of WiFi points or cell towers. This can happen if no cell towers or access points are valid or recognized.

To confirm that this is the issue, set considerIp to false in your request. If the response is a 404, you've confirmed that your wifiAccessPoints and cellTowers objects could not be geolocated.