We have published approximately 17,000 Derja.Ninja cards on Brainscape, available for free to Brainscape users. These cards include audio.
Brainscape is available as an app from the App Store and from the Google Play store. Install the app, and then search for "Derja Ninja". You can also use Brainscape from your web browser.
Note: if you do sign up for Brainscape, please be aware that other users can see the names of other learners in the same class. If you wish to preserve your anonymity, we recommend using a pseudonym when signing up to Brainscape.