Localize.drupal.org hosts an amazing number of language translations, and we are eager to provide the fruits to you via different download methods.
Use l10n_update module (for Drupal 7 and earlier)
This is the best way to get translations and updates to them from the community automatically. The localization update module automates translation downloads from ftp.drupal.org using metadata about the modules and themes you are running as well as the translations provided on localize.drupal.org.
This feature is built into Drupal 8.
Use ftp.drupal.org manually
Translation files are exported to ftp.drupal.org from the database as often as possible. You can navigate the FTP server from the web interface. The root of the translation downloads is at http://ftp.drupal.org/files/translations/. You'll find downloads separated by core compatibility and project name. For example, http://ftp.drupal.org/files/translations/7.x/ lists all the Drupal 7 translation files we made available, while http://ftp.drupal.org/files/translations/7.x/drupal/ is the 7.x translation files for Drupal core itself. Browse around and find your translation files there. The files exported here only contain approved translations (and lack source strings without translations for size optimization). https://localize.drupal.org/translate/downloads provides an easy to use interface to look up files.
Contribute to translations and export
If you are a contributor to a translation group, you can also download .po files from the latest version of the database state. We do not recommend the use of this method on a daily basis, since it puts load on our database. We specifically came up with the static files generated on ftp.drupal.org to avoid our database loaded with exports for regular use. If you contribute to the translation efforts however, you'll find the most up to date version by exporting directly from the database. This may include suggestions only or suggestions as well as translations. Given that suggestions not yet approved did not get the quality control that approved translations have, using these on a live site is not advised.
Frequency of ftp.drupal.org file updates
As of this writing, we have about 65 thousand project releases and 112 translation teams, so we have about 7.3 million files to regenerate continually as new translations are entered. We only regenerate files as needed, if translations changed since the last file date. See https://localize.drupal.org/translate/downloads for information on file creation times and when did we last check that the file was fully up to date for the current approved translations if interested in the finer details.
If you have bugs to report about our downloads, see http://localize.drupal.org/issues for more information.
