Fluent Editor, an ontology editor, is an Award Winning comprehensive tool for editing and manipulating complex ontologies that uses Controlled Natural Language and is compatible with Semantic Web standards. Fluent Editor provides one with a more suitable for human users alternative to XML-based OWL editors. It’s main feature is the usage of Controlled English as a knowledge modeling language. Supported via Predictive Editor, it prohibits one from entering any sentence that is grammatically or morphologically incorrect and actively helps the user during sentence writing. The Controlled English is a subset of Standard English with restricted grammar and vocabulary in order to reduce the ambiguity and complexity inherent in full English.