Anki (software)

Anki is a free and open-source flashcard program that utilizes spaced repetition. Spaced repetition has been shown to increase rate of memorization.[3] "Anki" (暗記) is the Japanese word for "memorization".[4] The SM2 algorithm, created for SuperMemo in the late 1980s, forms the basis of the spaced repetition methods employed in the program. Anki's implementation of the algorithm has been modified to allow priorities on cards and to show flashcards in order of their urgency. The cards are presented using HTML and may include text, images, sounds, videos,[5] and LaTeX equations. The decks of cards, along with the user's statistics, are stored in the open SQLite format.

Developer(s)Damien Elmes
Initial releaseOctober 5, 2006 (2006-10-05)
Stable release
2.1.15 / September 19, 2019 (2019-09-19)[1]
Written inPython
Operating systemWindows, macOS, Linux, FreeBSD; Android and iOS (special versions)
  • Windows: 28.3 MB
  • macOS: 31.7 MB
  • Linux: 29.1–30.1 MB
  • Android: 8.0 MB
  • iOS: 25.1 MB
TypeFlashcard spaced repetition
LicenseGNU AGPL v3[2] (desktop and Android)



Cards are generated from information stored as "notes". Notes are analogous to database entries and can have an arbitrary number of fields. For example, with respect to learning a language, a note may have the following fields and example entries:

  • Field 1: Expression in target language – "gâteau"
  • Field 2: Pronunciation – [sound file with the word "gâteau" pronounced]
  • Field 3: Meaning of expression in familiar language – "cake"

This example illustrates what some programs call a three-sided flashcard, but Anki's model is more general and allows any number of fields to be combined in various cards.

The user can design cards that test the information contained in each note. One card may have a question (expression) and an answer (pronunciation, meaning).

By keeping the separate cards linked to the same fact, spelling mistakes can be adjusted against all cards at the same time and Anki can ensure that related cards are not shown in too short a spacing.

A special note type allows for generation of cloze deletion cards (in Anki 1.2.x, those were ordinary cards with cloze markup added using a tool in the fact editor).


Anki supports synchronization with a free (but proprietary) online server called AnkiWeb.[6] This allows users to keep decks synchronized across multiple computers, and to study online or on a cell phone.

There is a third-party open source (AGPLv3) AnkiServer software which users can run on their own local computers or servers, though it is not compatible with recent Anki versions. It also provides a RESTful API for manipulating Anki collections.[7]

Japanese and Chinese reading generation

Anki can automatically fill in the reading of Japanese and Chinese text. Since version, these features are in separate plug-ins.


More than 500 add-ons for Anki are available,[8] often written by third-party developers.[9] They provide support for speech synthesis, enhanced user statistics, image occlusion, incremental reading, allow for more efficient editing and creation of cards through batch editing, modify the GUI (such as through intermittent display of puppies), simplify import of flashcards from other digital sources, etc.

Shared Decks

While Anki's user manual encourages the creation of one's own decks for most material, there is still a large and active database of Shared Decks that users can download and use.[10] Available decks range from foreign language decks (often constructed with frequency tables) to geography, physics, biology, chemistry and more. Various medical science decks, often made by multiple users in collaboration, are also available.


Anki's scheduling algorithm is based on an older version of the SuperMemo algorithm (SM2). The Anki author states that versions 3–5 of the SuperMemo algorithm are more susceptible to incorrect scheduling.[11][12] The latest SuperMemo algorithm in 2019 is SM18.[13]

Mobile versions

The following smartphone/tablet and Web clients are available as companions to the desktop version:[14][15][16]

  • AnkiMobile[17] for iPhone, iPod touch or iPad (paid)
  • AnkiWeb[18] (online server, free to use; includes add-on and deck hosting)
  • AnkiDroid[19] for Android (free of charge, under GPLv3; by Nicolas Raoul)

The flashcards and learning progress can be synchronized both ways with Anki using AnkiWeb. With AnkiDroid it is possible to have the flashcards read in several languages using text-to-speech (TTS). If a language does not exist in the Android TTS engine (e.g. Russian in the Android version Ice Cream Sandwich), a different TTS engine such as SVOX TTS Classic can be used.


The oldest mention of Anki that the developer, Damien Elmes, could find in 2011 was dated October 5, 2006, which was thus declared Anki's birthdate.[20]

In 2010, Roger Craig obtained the then-all-time record for single-day winnings on the quiz show Jeopardy![21] after using Anki to memorize a vast number of facts.[22]

Version 2.0 was released on 2012-10-06.

Version 2.1 was released on 2018-08-06.


While Anki may primarily be used for language learning or a classroom setting, many have reported other uses for Anki: scientist Michael Nielsen using it to remember complex topics in a fast-moving field[23], others using it to remember memorable quotes, the faces of business partners or medical residents, or remember business interviewing strategies.

Copera Inc.'s Anki for Palm OS

An unrelated flashcard program called Anki for Palm OS[24] was created by Copera, Inc. (formerly known as Cooperative Computers, Inc.) and released at the PalmSource conference in February 2002. Anki for Palm OS was sold from 2002 to 2006 as a commercial product. In late 2007, Copera, Inc. decided to release Anki for Palm OS as freeware.

See also


  1. "Releases". Github. Retrieved 1 September 2019.
  2. "LICENSE". Anki. Damien Elmes. 6 May 2016 via GitHub.
  3. Smolen, Paul; Zhang, Yili; Byrne, John H. (25 January 2016). "The right time to learn: mechanisms and optimization of spaced learning". Nature Reviews Neuroscience. 17 (2): 77–88. arXiv:1606.08370. Bibcode:2016arXiv160608370S. doi:10.1038/nrn.2015.18. PMC 5126970. PMID 26806627.
  4. wikt:暗記
  5. Played in a separate MPlayer window.
  6. "Anki - friendly, intelligent flashcards".
  7. "dsnopek/anki-sync-server". GitHub. 2019-07-24.
  8. "Add-ons for Anki 2.0".
  9. "Writing Anki 2.0.x Add-ons".
  10. "Anki Manual". Retrieved 2018-08-26.
  11. "Anki Manual".
  12. "Google Groups".
  13. "Three Decades: From SuperMemo 1.0 to SuperMemo 18.0". 22 Sep 2019.
  14. "Anki - powerful, intelligent flashcards". 29 Oct 2017. AnkiMobile is a paid companion to the free computer program,
  15. "Anki-Android Wiki: FAQ: Do I need Anki Desktop too?". 29 Oct 2017. AnkiDroid is designed primarily as a tool for reviewing cards created with Anki Desktop, rather than as a complete replacement for it.
  16. "About - AnkiWeb". 29 Oct 2017. AnkiWeb is intended to be used in conjunction with the computer version of Anki. While it is possible to create basic text-only cards and review them using only AnkiWeb,
  17. "Anki - powerful, intelligent flashcards".
  18. "Anki - friendly, intelligent flashcards".
  19. "Anki on Android". 2019-07-26.
  20. Happy birthday, Anki!, a thread started by Damien Elmes in the ankisrs Google Group on 2011-10-05.
  21. Itzkoff, Dave (September 15, 2010). "Record Set On 'Jeopardy!'". The New York Times. Retrieved September 20, 2010.
  22. Baker, Stephen (2011). "How to Play the Game". Final Jeopardy: Man vs. Machine and the Quest to Know Everything. Houghton Mifflin Harcourt. p. 214. ISBN 978-0-547-48316-0. LCCN 2010051653. OCLC 651912283. OL 25136706M. Retrieved 25 April 2015.
  23. Coren, Michael J. "The latest brain hack to get ahead in Silicon Valley: flashcards". Quartz. Retrieved 2019-09-29.
  24. "About Anki for Palm OS". Mirror of old website.

Further reading

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