Apps similar to Protégé include TheBrain, which has a free version. Other options are Visual Understanding Environment, Fluent Editor, Onto4ALL and CmapTools. In total there are eight Mind Mapping Tools like Protégé for Windows, the web, Mac, iPad and Linux.
TheBrain helps you organize all your Web pages, contacts, documents, emails and files in a context-driven visual map.
United States
Visual Understanding Environment (VUE) is a mind-mapping and concept-mapping tool. It is also a non-linear presentation program.
United States
An ontology editor focused on providing a seamless experience for users working with OWL ontologies. It supports the editing of structured ontologies and offers various validation and reasoning tools.
Poland
EU
Onto4ALL Is a free graphical editor capable of creating, editing and exporting ontologies being guided by an warnings console, an ontological building rules tab and an extensive palette of ontological classes and relationships.
Brazil
concept maps on servers, edit their maps synchronously (at the same time) with other users on the Internet, and search the web for information relevant to a concept map.
3D Topicscape is a Personal Information Manager that provides a template loosely based on mind-mapping or concept mapping. It presents the mind map as a 3D scene where each node is a cone (or pyramid, or variation on such a shape). It can also display in a 2D format.
United Kingdom
Unilexicon™ a visual editor and taxonomy manager for authoring controlled vocabularies with a content tagging extension.
