Simplest way to detect client locale in PHP

You can do some IP comparaison without having a whole library to do it.

Solution #1

Use an API, this way nothing is needed from your side. This is a web API that let you know the country:

 Example: http://api.hostip.info/get_html.php?ip=12.215.42.19
 Return : Country: UNITED STATES (US)

Solution #2

But, Have you think to use the browser agent language? You might be able to know the type of english from it.

Solution #3

This website called BlockCountry let you have a list of IP by country. Of course, you do not want to block, but you can use the list of IP and compare them (get all US IP...) this might not be accurate...

Not guaranteed, but most browsers submit an Accept-Language HTTP header that specifies en-us if they're from the US. Some older browsers only said they are en, though. And not all machines are set up correctly to indicate which locale they prefer. But it's a good first guess.

English-UK based-users usually set their system or user locale to English-UK, which in default browser configurations should result in en-gb as the Accept Language header. (An earlier version of this said en-uk; that was a typo, sorry.) Other countries also have en locales, such as en-za (south africa), and, primarily theoretically, combinations like en-jp are also possible.

Geo-IP based guesses will less likely be correct on the preferred language/locale, however. Google thinks that content-negotiation based on IP address geolocation makes sense, which really annoys me when I'm in Japan or Korea...

You can check out the HTTP_ACCEPT_LANGUAGE header (from $_SERVER) that most browsers will send.

Take a look at Zend_Locale for an example, or maybe you might even want to use the lib.

PHP provides a function since 5.3.0 to parse the $_SERVER['HTTP_ACCEPT_LANGUAGE'] variable into a locale.

$locale = Locale::acceptFromHttp($_SERVER['HTTP_ACCEPT_LANGUAGE']);
echo $locale; // returns "en_US"

Documentation: https://www.php.net/manual/en/locale.acceptfromhttp.php