Protege

Protege is one of the most popular ontology editors and knowledge-base frameworks available today. It is a free, open source software that is trusted by developers all around the world. The Protege platform comes equipped with two main ways of modeling ontologies: the Protege-Frames editor and the Protege-OWL editor.

Protege is incredibly versatile, allowing users to export their ontologies into a variety of formats, including OWL, RDF(S), and XML Schema. This makes it an ideal tool for developers who want to work with multiple formats simultaneously.

Built on a powerful Java foundation, Protege is also highly extensible. It provides a plug-and-play environment that enables users to easily add new features and functionality to their applications. This makes it an excellent choice for developers who value agility and flexibility in their software development process.

In conclusion, Protege is an outstanding ontology editor and knowledge-base framework that has earned its reputation as a reliable and versatile tool for software development. It is highly recommended for anyone looking for a powerful, flexible, and easy-to-use ontology editor.