Anki and Spaced Repetition

Polar supports native integration with Anki via the Polar Connect add-on.

This allows for annotations on document and connecting flashcards to these annotations and then synchronizing them directly to Anki.

Polar supports a robust annotation system internally with features like text and area highlights, and allowing comments and flashcards to be attached directly to the highlights.

This allows you to create flashcards but keep context associated with the flashcards.

The context is important. When using spaced repetition you don’t want to forget the context in the future. You might forget about a topic or want to review and knowing the context is extremely important.

Deck mapping

By default Polar stores all Anki cards in the ‘Default’ deck.

You can change the deck per document by setting a tag with a deck: prefix.

For example, if you want to store things in the ‘Technology’ deck you just tag the document you’re reading as ‘deck:Technology’.

NOTE: In Polar versions prior to 1.8.0 we used a ‘deck per doc’ strategy where a new deck was created per document. Not many users liked this and we removed it in 1.8.0. Technically it’s still supported but needs to be re-enabled.


We now support sub-decks and these can be done with deck:compsci/linux for example with a forward slash building the sub-deck hierarchy.

We replace it with the internal Anki :: but in Polar we want to keep hierarchies represented by a forward slash.

Card Types

Both cloze deletion and front/back card types are supported.

Cards also support rich text formatting (bold, italic, etc) as well as images.


Install the Polar Connect add-on and restart Anki. At this point Polar can sync to Anki properly.

Note that we used to recommend Anki Connect but we suggest you install Polar Connect now which will have more functionality.


Once Polar Connect is running, go to Tools | Sync Flashcards to Anki from within the Document Repository.



If you have any issues connecting Anki make sure you don’t have a firewall in place. Polar Connect runs Anki on a specific port and Polar needs to connect via TCP to sync your flashcards.

International Users!

*IMPORTANT If you’re using an non-English version of Anki you have to create note types for “Basic” and “Cloze” otherwise sync will fail. Changing the language doesn’t re-create the note types unfortunately. We’re working on a fix for this issue.


  • No current ability to update flashcards. Polar currently lacks a flashcard update UI so this needs to be added to Polar before we can implement this in Anki sync.

  • Anki must have Polar Connect. This will always be a hard requirement but we might create a Polar Sync plugin for Anki.

  • No support for nested decks. Each deck is created at the root. If you move it the new deck will be created. We will have a fix for this in the future.

  • All flashcards are always sync’d each time. This is probably going to be slower for larger decks but we plan to implement differential sync in the future.


We plan on eventually supporting the following features when creating flashcards:

  • Preserving the original context URL so that you can link into polar and have it open the document direction

  • Storing additional fields in Anki including the name of the document, original text content of the highlight, possibly images of the highlight that the flashcard is bound to.