Rikaichan is a popup Japanese-English/German/French/Russian dictionary tool for Firefox, Thunderbird and Seamonkey.

  • Simple to use, just hover the mouse on top of a Japanese word.
  • Automatically de-inflects verbs and adjectives.
  • Has an optional toolbar that allows you to manually type the word to lookup.
  • Detailed kanji view shows meaning/keyword in English, on/kun readings, and other information.
  • Hiragana, katakana and half-width katakana are treated the same making it possible to lookup stylized/emphasized words.

Download the Firefox/Thunderbird/Seamonkey add-on
Requires: Firefox 4.x+, Thunderbird 4.x+, Seamonkey 2.x+

Rikaichan 2.09
Rikaichan 3.00a1 (pre-release / may be buggy)

Installing in Thunderbird?
  • Right-click the link, select Save As and save the *.xpi file somewhere in your computer.
  • In Thunderbird, open the Tools menu, click Addons, then click the Install button and find the downloaded *.xpi file.
Dictionary Files
(install one or more)

Japanese - Dutch
Japanese - English (recommended)
Japanese - French
Japanese - German
Japanese - Hungarian
Japanese - Russian
Japanese Names (recommended)
More... (getrcx)
More... (addons.mozilla.org)

Importing Entries
The following is a very basic tool that will allow you to append an EDICT-like formatted file to an existing dictionary.


To start, click Tools, then RCX Merge. It will popup a series of dialogs asking for the file (in plain-text EDICT format), the character encoding of that file (UTF-8, Shift-JIS or EUC-JP), and which existing dictionary to use.

Thank you!

Todd Rudick, James William Breen, Electronic Dictionary Research & Development Group, Michael Raine, Josh Glover, Zork Zero, and other contributors -- Thank you for making Rikaichan possible!