Functions vary between versions for different platforms, and the following list is not exhaustive.
As of April 2019,[update] the latest version for Windows is 31.1.6; for macOS, 31.0.3; for iOS, 1.6.2; and for Android, 1.8.15.3 They are available via the ATOK Passport subscription and an annual subscription which comes with Ichitaro.4 Linux, OS/2, Palm OS, Pocket PC, and Windows CE are no longer supported.5
KTIS and ATOK was originally a component of JustSystems' word processor software. Ichitaro released in 1985 allowed the use of ATOK 4 in other MS-DOS applications of the PC-98 platform. ATOK 7 was bundled with Ichitaro 4, and was available as a standalone product in 1992.6 In DOS era, ATOK was spreading with Ichitaro despite competition from VJE, Matsutake, and some other software. Windows 3.1, the first retail version of Japanese Windows, bundled the Microsoft IME (MS-IME) input method. MS-IME 97 contained notable improvements, and was bundled with a new retail box of Windows 95 and Office 97. The difference between ATOK and MS-IME went smaller.7
In 2008, JustSystems began a subscription service, ATOK Passport.8 ATOK 2017 was the last version to be physically shipped as boxed software.9
Sun Microsystems chose ATOK as their input method when running under the JP locale in Solaris 10 and above, enhancing Sun's already strong Japanese language support.10
For embedded systems, JustSystems has developed +ATOK. Some Japanese mobile phones, PDAs, video game consoles (PSP, PS3 and Wii), digital video recorders, automotive navigation systems come with +ATOK.
国友, 正彦 (1989). 最新日本語入力FP対決 ATOK 7 VS VJE-β Ver.2.1. ASCII (in Japanese). 13 (9): 249–256. ISSN 0386-5428. 最新日本語入力FP対決 ATOK 7 VS VJE-β Ver.2.1 ↩
日本語入力システムとは. ATOK.com. 2010-05-27. Archived from the original on 2019-04-21. Retrieved 2019-04-22. 日本語入力システムとは ↩
個人向け製品の新元号への対応状況. JustSystems. 2019-04-19. Retrieved 2019-04-22. 個人向け製品の新元号への対応状況 ↩
井上, 翔 (2018-12-04). ATOK for Windowsに「漢字の絞り込み」と「地名変換」を強化した新バージョン 月額版は2019年2月1日から配信. ITmedia PC USER. Retrieved 2019-04-22. ATOK for Windowsに「漢字の絞り込み」と「地名変換」を強化した新バージョン 月額版は2019年2月1日から配信 ↩
"サポート製品一覧". JustSystems. 2018-08-23. Retrieved 2019-04-22. http://support.justsystems.com/jp/list/index.html ↩
先進の日本語システム「ATOK」の進化. JustSystems. 1998-10-23. Archived from the original on 1999-02-02. Retrieved 2019-04-22. 先進の日本語システム「ATOK」の進化 ↩
Abe, Keisuke (2002-08-24). 日本語入力プログラムの歴史(MS-DOS~Windows). Retrieved 2019-05-11. 日本語入力プログラムの歴史(MS-DOS~Windows) ↩
三柳, 英樹 (2011-11-08). 「ATOK Passport」提供開始、Windows/Mac/Android向けATOKが月額300円. INTERNET Watch. Retrieved 2019-04-22. 「ATOK Passport」提供開始、Windows/Mac/Android向けATOKが月額300円 ↩
劉, 尭; 若杉, 紀彦 (2017-12-05). 【速報】新ATOK、パッケージ版廃止で月額制のみに ~新バージョンは2018年2月1日提供開始. PC Watch. Impress Corporation. Retrieved 2019-04-21. 【速報】新ATOK、パッケージ版廃止で月額制のみに ~新バージョンは2018年2月1日提供開始 ↩
"ATOK for Solaris ユーザーガイド". Documentation. Sun Microsystems. 2006. Retrieved 2019-04-22. https://docs.oracle.com/cd/E19253-01/819-6261/book-info/index.html ↩