edit-on Pro provides a basic spell checker functionality. The editor comes with the following 17 dictionaries:

 

 

* American/British/Canadian English: 100,000 words

* German: 295,000 words. Includes separate pre- and post-reform German dictionaries

* French: 137,000 words. Contains both European and Canadian spelling.

* Spanish: 288,000 words. Contains European, Mexican, and South American words.

* Italian: 283,000 words.

* Dutch: 178,000 words. Includes the "new spelling" ("De Nieuwe Spelling").

* Swedish: 110,000 words.

* Finnish: 251,000 words.

* Norwegian: 95,000 words in the Bokmål dialect.

* Danish: 102,000 words

* Brazilian Portuguese: 119,000 words

* Portuguese (Iberian): 135,000 words

* American/British Medical: Supplement to the English dictionaries containing 133,000 words related to anatomy, diseases, health care, generic and trademark drug names, and medical research.

* Legal: Supplement to the English dictionaries containing 4,500 words related to jurisprudence, law, criminology, and law enforcement. Includes separate American and British dictionaries.

 

 

The spell checker language can be modified and new words can be added to a custom dictionary at runtime. In addition, the editor also offers a JavaScript API which allows the retrieval of selected text, i.e. a particular word within the editor’s editing area. The API, in combination with a Custom Button and server-side programming, enables the users to add a selected word to the editor's custom dictionary.