Antheia is a plain text editor that enables users to type hundreds of different characters by entering (usually fairly easy to remember) sequences of 1, 2 or 3 ASCII-characters. The character that will be inserted into the current document will also depend upon the script mode that the application is switched to. For instance, if you press the key that would normally be used to type the letter y, Antheia will display the same letter y in Latin mode, but the Greek letter υ in Greek mode, the Cyrillic letter ы in Cyrillic mode and the Thai letter ย in Thai mode. An example of a sequence that consists of more than one character is 'a (single quote plus small letter a), which results in Antheia converting this sequence to á in Latin mode and to ά in Greek mode.

Antheia currently supports the following script modes:

- ASCII*
- Cyrillic
- Greek (monotonic & polytonic)
- IPA (International Phonetic Alphabet)
- Latin
- Thai

* In script mode ASCII no character conversion occurs, so when you type for instance 'a in this mode, a single quote followed by a small letter a will be inserted into the current document. Despite its name it is possible to enter non-ASCII characters in this mode, for instance by using the alt-key together with the numeric keys of the keyboard.

.NET Framework 2.0 is required.