Q15991270

LanguageTool is a free and open-source grammar, style, and spell checker, and all its features are available for download. The LanguageTool website connects to a proprietary sister project called LanguageTool Premium (formerly LanguageTool Plus), which provides improved error detection for English and German, as well as easier revision of longer texts, following the open-core model.

==Overview== LanguageTool was started by Daniel Naber for his diploma thesis in 2003 (then written in Python). It now supports 31 languages, each developed by volunteer maintainers, usually native speakers of each language. Based on error detection patterns, rules are created and then tested for a given text. The core app itself is free and open-source and can be downloaded for offline use. Some languages use 'n-gram' data, which is massive and requires considerable processing power and I/O speed, for some extra detections. As such, LanguageTool is also offered as a web service that does the processing of 'n-grams' data on the server-side. LanguageTool "Premium" also uses n-grams as part of its freemium business model.