Wordfast Classic, Pro, and Anywhere allow for using Google Translate, the Google machine translation service, as well as other machine translation services all of which are offered by third-party providers. With this feature activated, your segments are automatically machine-translated whenever no Translation Memory match is available.
Note that Wordfast is not responsible for and does not guarantee the reliability or quality of Google Translate, Microsoft Translator, or any other machine translation service. Wordfast only provides a way to access those machine translation services automatically. It has no way to guarantee the service will work well at all times.
It is noteworthy that when you activate a machine translation service, Wordfast sends source segments ONLY to the machine translation provider you selected so that they can be machine-translated; however, it does NOT send back your translation, i.e. target segments, to the machine translation provider. On the other hand, if you do not activate the machine translation option, Wordfast does NOT send anything outside your machine at all.
Important: as of fall 2011, Google charge for using Google Translate from within third-party tools, such as Wordfast. In order to access GT from any Wordfast tool, you need to obtain your API key for a fee you pay directly to Google.
To more about how to activate Machine Translation services, please check these articles: