Crowdin.net is an online translation tool for crowd sourced translations. Check out the Crowdin video to get an idea of how it works:
This is very easy!
Each string can have multiple suggested translations by different translators. Some users have Proofreader permissions that will allow them to review all translations and select one of the suggested translations as the 'approved' translation.
Users with Manage permissions can use the Crowdin CLI tool to upload source (resource bundles) to Crowdin. To use the CLI tool you will need a config file that defines which files contain i18n strings. You can find this file attached to this page. You will need to obtain an API key to interact with the CrowdIn API.
To upload source files from your SVN working copy to CrowdIn:
crowdin-cli upload sources
To upload translations files from your SVN working copy to CrowdIn use:
crowdin-cli upload translations
To download translation files from CrowdIn to your SVN working copy use:
If you only want to synch files for a specific language you can use the above command in combination with the language parameter. For example:
crowdin-cli upload translations -lNL-nl
Just contact the project owner or an existing project manager.
Please read the instructions at the bottom of this page