TanSanC

I would use a web service that can return JSON (along with jQuery to make things simpler). Below are all the free active IP lookup services I could find and the information they return. If you know of any more, then please add a comment and I'll update this answer.

db-ip.com

http://api.db-ip.com/addrinfo?api_key=<your_api_key>&addr=<your_ip_address>

Returns:

{
  "address": "116.12.250.1",
  "country": "SG",
  "stateprov": "Central Singapore",
  "city": "Singapore"
}

Limitations:

• 2,500 requests per hour
• Doesn't support JSONP callbacks
• Requires IP address parameter

geobytes.com

$.getJSON('//gd.geobytes.com/GetCityDetails?callback=?', function(data) {
  console.log(JSON.stringify(data, null, 2));
});

Returns:

{
  "geobytesforwarderfor": "",
  "geobytesremoteip": "116.12.250.1",
  "geobytesipaddress": "116.12.250.1",
  "geobytescertainty": "99",
  "geobytesinternet": "SA",
  "geobytescountry": "Saudi Arabia",
  "geobytesregionlocationcode": "SASH",
  "geobytesregion": "Ash Sharqiyah",
  "geobytescode": "SH",
  "geobyteslocationcode": "SASHJUBA",
  "geobytescity": "Jubail",
  "geobytescityid": "13793",
  "geobytesfqcn": "Jubail, SH, Saudi Arabia",
  "geobyteslatitude": "27.004999",
  "geobyteslongitude": "49.660999",
  "geobytescapital": "Riyadh ",
  "geobytestimezone": "+03:00",
  "geobytesnationalitysingular": "Saudi Arabian ",
  "geobytespopulation": "22757092",
  "geobytesnationalityplural": "Saudis",
  "geobytesmapreference": "Middle East ",
  "geobytescurrency": "Saudi Riyal",
  "geobytescurrencycode": "SAR",
  "geobytestitle": "Saudi Arabia"
}

Limitations:

• 16,384 requests per hour
• Returns the wrong location (I'm in Singapore, not Saudi Arabia)

geoplugin.com

$.getJSON('//www.geoplugin.net/json.gp?jsoncallback=?', function(data) {
  console.log(JSON.stringify(data, null, 2));
});

Returns:

{
  "geoplugin_request": "116.12.250.1",
  "geoplugin_status": 200,
  "geoplugin_credit": "Some of the returned data includes GeoLite data created by MaxMind, available from <a href=\\'http://www.maxmind.com\\'>http://www.maxmind.com</a>.",
  "geoplugin_city": "Singapore",
  "geoplugin_region": "Singapore (general)",
  "geoplugin_areaCode": "0",
  "geoplugin_dmaCode": "0",
  "geoplugin_countryCode": "SG",
  "geoplugin_countryName": "Singapore",
  "geoplugin_continentCode": "AS",
  "geoplugin_latitude": "1.2931",
  "geoplugin_longitude": "103.855797",
  "geoplugin_regionCode": "00",
  "geoplugin_regionName": "Singapore (general)",
  "geoplugin_currencyCode": "SGD",
  "geoplugin_currencySymbol": "&#36;",
  "geoplugin_currencySymbol_UTF8": "$",
  "geoplugin_currencyConverter": 1.4239
}

Limitations:

• 120 requests per minute

hackertarget.com

http://api.hackertarget.com/geoip/?q=<your_ip_address>

Returns:

IP Address: 116.12.250.1
Country: SG
State: N/A
City: Singapore
Latitude: 1.293100
Longitude: 103.855797

Limitations:

• 50 requests per day
• Only returns plain text
• Requires IP address parameter

ip-api.com

$.getJSON('//ip-api.com/json?callback=?', function(data) {
  console.log(JSON.stringify(data, null, 2));
});

Returns:

{
  "as": "AS3758 SingNet",
  "city": "Singapore",
  "country": "Singapore",
  "countryCode": "SG",
  "isp": "SingNet Pte Ltd",
  "lat": 1.2931,
  "lon": 103.8558,
  "org": "Singapore Telecommunications",
  "query": "116.12.250.1",
  "region": "",
  "regionName": "",
  "status": "success",
  "timezone": "Asia/Singapore",
  "zip": ""
}

Limitations:

• 150 requests per minute

ipify.org

$.getJSON('//api.ipify.org?format=jsonp&callback=?', function(data) {
  console.log(JSON.stringify(data, null, 2));
});

Returns:

{
  "ip": "116.12.250.1"
}

Limitations:

• None (unlimited bandwidth)

ipinfo.io

$.getJSON('//ipinfo.io/', function(data) {
  console.log(JSON.stringify(data, null, 2));
});

Returns:

{
  "ip": "116.12.250.1",
  "hostname": "No Hostname",
  "city": "Singapore",
  "region": "",
  "country": "SG",
  "loc": "1.2931,103.8558",
  "org": "AS3758 SingNet"
}

Limitations:

• 1,000 requests per day

ipinfodb.com

$.getJSON('//api.ipinfodb.com/v3/ip-city/?key=<your_api_key>&format=json&callback=?', function(data) {
  console.log(JSON.stringify(data, null, 2));
});

Returns:

{
  "statusCode": "OK",
  "statusMessage": "",
  "ipAddress": "116.12.250.1",
  "countryCode": "SG",
  "countryName": "Singapore",
  "regionName": "Singapore",
  "cityName": "Singapore",
  "zipCode": "048941",
  "latitude": "1.28967",
  "longitude": "103.85",
  "timeZone": "+08:00"
}

Limitations:

• Two requests per second
• Requires registration to get your API key

ip-json

http://ip-json.rhcloud.com/json

Returns:

{
  "site": "http://ip-json.rhcloud.com",
  "city": "Singapore",
  "region_name": null,
  "region": "00",
  "area_code": 0,
  "time_zone": "Asia/Singapore",
  "longitude": 103.85579681396484,
  "metro_code": 0,
  "country_code3": "SGP",
  "latitude": 1.2930999994277954,
  "postal_code": null,
  "dma_code": 0,
  "country_code": "SG",
  "country_name": "Singapore",
  "q": "116.12.250.1"
}

Limitations:

• Quota not stated, but may be limited by OpenShift PaaS
• Doesn't support JSONP callbacks

jsonip.com

$.getJSON('//jsonip.com/?callback=?', function(data) {
  console.log(JSON.stringify(data, null, 2));
});

Returns:

{
  "ip": "116.12.250.1",
  "about": "/about",
  "Pro!": "http://getjsonip.com"
}

Limitations:

• None (unlimited bandwidth)

jsontest.com

$.getJSON('//ip.jsontest.com/?callback=?', function(data) {
  console.log(JSON.stringify(data, null, 2));
});

Returns:

{
  "ip": "116.12.250.1"
}

Limitations:

• Goes down a lot (over quota), so I wouldn't use it for production

snoopi.io

http://api.snoopi.io/v1/

Returns:

{
  "remote_address": "116.12.250.1",
  "requested_address": "116.12.250.1",
  "requested_time": "11:25:35 pm",
  "requested_date": "January 31, 2016",
  "CountryCode": "SG",
  "Region": null,
  "Region_Full": "Singapore",
  "City": "Ubi",
  "PostalZip": "96940",
  "TimeZone_Name": "Asia\/Singapore",
  "Latitude": "1.31865",
  "Longitude": "103.894"
}

Limitations:

• 2,500 requests per day
• Doesn't support JSONP callbacks