Anki Official

These links below are from the official Anki project.

Desktop

You can download the Anki desktop on the following link: Anki - powerful, intelligent flashcards

iOS

‎AnkiMobile Flashcards is the official app for iPhone and iPad users. Note that the price $24.99 goes directly to supporting the app. When purchasing make sure you are getting this one

Anki Manual

The Anki Manual has more detail on how Anki works.