Hydra is a tool for editing, viewing, searching and validating wordnet. The Hydra API for wordnet processing uses abstract language independent of the data representation, the tool supports a multiple-user concurrent access for editing and browsing arbitrary number of monolingual wordnets, it optimizes data visualization as well as enhances editing, undo/redo functions, etc. The search engine works with the wordnet modal language. The language abstracts the internal data representation and is expressive for the most of the tasks in processing wordnets. Provided that a given wordnet property is definable as a formula in the modal language, the tool determines all the objects in the wordnet structure validating the formula, and hence the property, covering an automatic consistency validation. As a platform-independent system, Hydra has been successfully tested under Linux and Windows.