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Add a country dropdown that defaults from IP

· 3 min read · My Geocode · #ip-lookup#forms#country-selection#ux

A country dropdown that defaults to whatever a visitor's IP address suggests saves most people a scroll through a long list, as long as it still lets them change it when the default is wrong.

Getting the default value

Look up the visitor's IP address on your server when the page is requested, and read the country_code field from the response to set as the dropdown's selected option before the page is even sent to the browser.

GET /v1/ip?ip=192.0.2.15
{
  "status": "ok",
  "ip": "192.0.2.15",
  "version": 4,
  "found": true,
  "country": "Spain",
  "country_code": "ES",
  "region": "Madrid",
  "city": "Madrid",
  "postcode": "28001",
  "lat": 40.4168,
  "lon": -3.7038,
  "timezone": "Europe/Madrid",
  "asn": 5678,
  "org": "Example Networks"
}

Rendering it server-side

Since this happens entirely server-side, before rendering the page, there is no flash of a wrong default followed by a correction in the browser, which is what happens with client-side approaches that call out after the page has already loaded. Set the selected attribute on the matching option directly in the HTML you generate, matching country_code against whatever ISO codes your option values already use.

A second example: prefilling a checkout country field

The same call works just as well on a checkout page as on a signup form. Look up the shopper's IP once when the checkout page loads, match country_code to your shipping country list, and select it by default. Because the shipping country affects tax and delivery options shown further down the page, getting this right before the page renders avoids a jarring reflow later if the visitor had to correct it after everything else had already loaded around a wrong default.

Always allow a change

Treat the IP-based country as a starting point, not a locked-in answer. A visitor traveling, using a work VPN, or simply living somewhere their network provider's registered address does not match will need to pick a different option, so nothing about the form should assume the default is correct.

A common mistake to avoid

Do not cache the fully rendered page behind a CDN or reverse proxy without varying it by visitor, since a page rendered once for the first visitor's IP and then served from cache to everyone afterward will show that first visitor's country to every subsequent visitor regardless of where they actually are. If your pages are cached at all, either exclude this fragment from the cache or render it through a small server-side include that runs per request.

Handling a lookup that finds nothing

If found comes back false, which happens for some private or unallocated ranges, fall back to a neutral default, such as an empty selection or your most common country, rather than leaving the field in an undefined state.

IPv6 visitors work the same way

A visitor connecting over IPv6 gets the same country_code field back from the same endpoint, just resolved against a /48 network rather than a /24. Nothing about the dropdown logic needs to change based on which IP version made the request. See the IPv6 lookup docs if you want the version-specific details.

Cost of this feature

This is one request per new visitor session, cached for the session so a single visit does not trigger repeated lookups across multiple form pages. That keeps the feature well within the 2,500 free requests a day included with every key, or available from a single address without one, for any but the busiest sites.

A sensible default saves a scroll through a hundred-item list, and the visitor still has full control if it guesses wrong. Field details are on the IPv4 lookup docs.

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