Using the Language System

phpBB uses a language system to guarantee easy localisation. All strings presented to the user are first looked up in an internal dictionary. Thus it is also a requirement for Extensions to use said system for all output presented to the user. This chapter will show you how to use the language system and how to add your custom entries.

We generally refer to the name of the word in the dictionary as language key or language variable, to the returned value as language value or language string. Both together are a language entry. Language entries are collected in language files.


By convention, the language key should always be all-uppercase, using underscores to separate words.

Using the Language System in php

The object holding the language dictionary for the current user is the $language object (phpbb\language\language class). To get the translation of a language entry inside of php code, call the phpbb\language\language::lang() method:


You can also insert values into translated string. Use %s as placeholders for string in the language string and %d for integers:

// Language string: "My translation has a %s"
echo $language->lang('LANG_KEY', 'parameter');
// Output: "My translation has a parameter"

// Language string: "My translation has %d parameter"
echo $language->lang('LANG_KEY', 1);
// Output: "My translation has 1 parameter"


When using %d for plurals make sure to allow translators to use plurals according to their language. For more information see: Plurals


Many functions in phpBB automatically translate their arguments; passing the language key as an argument is usually enough.

The dictionary is not loaded into memory all at once, but is split up in several files, which have to be manually loaded on demand. The files are stored inside the language directory, named after its language tag, where one subdirectory is used for each installed language. The default language files are in the root of that subdirectory, while ACP language files go into the /acp subdirectory; email templates are placed in the /email subdirectory.


Files for extensions should be placed in the extension’s /language directory.

Loading language files

Loading from phpBB core

Additional language files can be loaded during user setup via the call to the phpbb\user::setup() method at the top of each accessible file. To do so, pass the name with the subdirectory but without extension as argument of setup.

// or
$user->setup(array('ucp', 'search'));

Since phpbb\user::setup() must only be called once, phpbb\language\language::add_lang() has to be used, to load additional language files, after phpbb\user::setup() has already been called.

// or
$language->add_lang(array('ucp', 'search'));

Loading from an extension

To load a file from an extension you need to use phpbb\language\language::add_lang() which takes the vendor + extension name as first argument and the array of language files as a second argument.

$language->add_lang('demo', 'acme/demo');
// or
$language->add_lang(array('demo', 'demo2'), 'acme/demo');

Using the Language System in template files

Language entries in Template Syntax are a major improvement since phpBB 3.0. There is no longer a need to manually assign these in the PHP file; language entries of loaded language files can be used automatically.

To use the language entry with the key MY_KEY in a template file, just write {L_MY_KEY} in the template (phpBB syntax) or {{ lang('MY_KEY') }} (new twig syntax).


If the language entry is going to be used inside of JavaScript, it must be properly escaped. This is easy to achieve by using {LA_MY_KEY} in the template (phpBB syntax) or {{ lang('MY_KEY')|e('js') }} (new twig syntax).


When using language entries in the JavaScript context with the new twig syntax, the following methods are possible:

  • {{ lang('MY_KEY')|escape('js') }} Twig’s native JavaScript context escape filter.

  • {{ lang('MY_KEY')|e('js') }} Short-hand version for calling escape using e.

  • {{ lang('MY_KEY')|escape('addslashes') }} phpBB’s legacy addslashes escape filter.

  • {{ lang('MY_KEY')|e('addslashes') }} Short-hand version for calling escape using e.

Add new entries

New language files should always be placed in their own files in the extensions directory.


When defining log entries and module names, make sure to load the language file, when the entries are being used.


When writing or editing a language file, make sure to save it using utf-8 encoding without BOM (Byte Order Mark). Otherwise the forum will not function properly. Some editors call that mode “utf8 cookie”.

// language/en/sample.php
 * This file is part of the phpBB Forum Software package.
 * @copyright (c) phpBB Limited <>
 * @license GNU General Public License, version 2 (GPL-2.0)
 * For full copyright and license information, please see
 * the docs/CREDITS.txt file.

if (empty($lang) || !is_array($lang))
    $lang = array();

// All language files should use UTF-8 as their encoding and the files must not contain a BOM.
// Placeholders can now contain order information, e.g. instead of
// 'Page %s of %s' you can (and should) write 'Page %1$s of %2$s', this allows
// translators to re-order the output of data while ensuring it remains correct
// You do not need this where single placeholders are used, e.g. 'Message %d' is fine
// equally where a string contains only two placeholders which are used to wrap text
// in a url you again do not need to specify an order e.g., 'Click %sHERE%s' is fine

$lang = array_merge($lang, array(
    'MY_LANGUAGE_KEY'         => 'A language entry',
    'MY_OTHER_LANGUAGE_KEY'   => 'Another language entry',
    'MY_TRICKY_LANGUAGE_KEY'  => 'This is a %slink%s',