Using IP address geolocation to improve UX

Streamline forms, personalise content and even improve fraud detection with just one API call.

Customer experience Daniel Cooper Published on 23 Apr 2025

IP address geolocation has been used for years to enhance user experience and security, and integrating this functionality is now more accessible than ever thanks to widely available APIs. In this post, we'll explore how IP address geolocation - using Postcoder as an example - can help streamline forms, personalise content and even improve fraud detection, often with just one API call.

IP address geolocation

Postcoder allows developers to retrieve detailed location data from an IP address, including:

Country and location information
Time zone
EU membership status
VPN detection

It's useful for personalising content, pre-filling forms or contributing to fraud checks.

Example request

https://ws.postcoder.com/pcw/PCW45-12345-12345-1234X/ipaddress/123.456.78.90

Example response

{
    "valid": true,
    "ipaddress": "123.456.78.90",
    "city": "Diss",
    "cityid": "2651214",
    "subdivision": "Norfolk",
    "subdivisioncode": "NFK",
    "country": "United Kingdom",
    "countrycode": "GB",
    "continent": "Europe",
    "continentcode": "EU",
    "postcode": "IP21",
    "latitude": "52.3652",
    "longitude": "1.2355",
    "timezone": "Europe/London",
    "eu": false,
    "possiblevpn": false
}

Features to look out for

When evaluating IP address geolocation APIs, developers may look for reliability, ease of integration and rich data. A well-designed API of this sort should minimise integration hurdles while providing accurate, actionable data.

1. Automatic IP address detection

Client-side integration with some IP address APIs can be awkward since JavaScript doesn't expose the client IP address. To remove this obstacle, Postcoder automatically uses the calling device's IP address when no IP address is supplied in the request path itself:

https://ws.postcoder.com/pcw/PCW45-12345-12345-1234X/ipaddress

{
    "valid": true,
    "ipaddress": "231.645.87.09",
    ...
    "country": "France",
    "countrycode": "FR",
    ...
}

2. Standardised location identifiers

Standard identifiers make it much easier to cross-reference location data with other internal or external systems - such as your own databases, third-party services like weather APIs or tools that calculate shipping. Look out for support for identifiers like GeoNames IDs and ISO 3166-X codes for countries and regions. Postcoder includes both in its responses, helping you link and layer location data with minimal effort.

3. Enhanced context beyond location

Beyond basic geographical data, additional context can help you further personalise a user's experience. Details like their time zone, EU membership status or whether their IP address is possibly linked to a VPN can be helpful for:

Setting GDPR-compliant defaults
Formatting dates and times appropriately
Flagging anonymised or potentially suspicious sessions

Postcoder includes all three in its responses, giving you more than just a location - it provides the kind of metadata that's genuinely useful for personalisation.

{
    ...
    "timezone": "Europe/London", // IANA time zone format
    "eu": false, // Is this country in the EU?
    "possiblevpn": true // Known VPN IP address?
}

Use cases for IP address geolocation

1. Auto-detect country to simplify forms

Long or complex forms are a top reason users abandon signups or checkouts. A recent Baymard study found 18% of users drop off because forms are too long or complicated. By detecting a user's country from their IP, you can pre-select the country on your delivery address form or localise the address fields on it.

2. Personalise content and formats

You can use geolocation to tailor a user's experience without asking them to choose settings manually:

Set the correct language or currency
Format dates and times locally
Show relevant regional content or legal notices
Display the right cookie banner depending on GDPR status

This creates a smoother, more trusted experience - especially for first-time visitors.

3. Trigger additional checks

IP address geolocation isn't just for convenience; it also helps identify unusual behaviour:

Country mismatch between billing address and IP address = possible fraud
VPN use = legitimate privacy concerns or masking
High-risk regions = trigger additional verification

While not a replacement for dedicated fraud tools, IP address geolocation provides a lightweight signal to layer with other risk indicators.

Best practices and privacy tips

Finally, to use IP address lookup responsibly and effectively, keep these points in mind:

Stay GDPR-compliant - IP addresses are considered personal data in the UK and EU
Let users override defaults - Always provide an option to correct auto-detected values
Cache results - Store results to reduce API calls by calling once per user session
Remember, geolocation is imprecise - The location data for an IP address usually reflects what the owning ISP has published for their range of addresses. With most broadband services, the city often points to the ISP or their data centre, not the actual user. Country-level data tends to be accurate, though

Try IP address geolocation for free

If you're evaluating IP address geolocation APIs for your website or app, don't forget to look for clear documentation and a free tier for testing. Postcoder's free trial includes simple docs and enough credit for 1000 requests. For more info, check out the docs and start testing it in your workflow.