TopQuadrant’s TopBraid Composer 
is the industry-leading enterprise-class modeling and application development environment. It provides comprehensive support for modeling ontologies and data, connecting data sources, designing queries, rules and semantic data processing chains, and developing Semantic Web applications.
TopBraid Composer is the leading industrial-strength RDF editor and OWL ontology editor, as well as the best SPARQL tool on the market.
As part of TopBraid Suite, Composer incorporates a flexible and extensible framework with a published API for developing semantic client/server or browser-based solutions that can integrate disparate applications and data sources.
Three versions are available – Free Edition, Standard Edition and Maestro Edition
Composer Free Edition
TopBraid Composer is a professional development environment for the W3C’s Semantic Web standards RDF Schema, the OWL Web Ontology Language and the SPARQL Query Language. The Free Edition is an entry-level tool for creating and editing RDF/OWL files and running SPARQL queries over them. The Free Edition also provides support for defining business rules and integrity constraints using SPARQL Rules (SPIN). The Free Edition does not include Support and Maintenance. Users of the Free Edition can send their questions to the TopBraid Composer mailing list, but priority will be given to customers using the commercial editions.
Composer Standard Edition
The Standard Edition greatly extends the Free Edition. It provides visual editors for RDF graphs and class diagrams, including the ability to generate SPARQL “by example” in the graph view. While the Free Edition can only be used to work with RDF/OWL files, the Standard Edition provides scalable database backends (such as Jena SDB/TDB, AllegroGraph, Oracle 11g and Sesame). It also provides automated conversion of XML, XSD, Excel, UML and other data sources. The Standard Edition can connect to relational databases making it possible to run SPARQL queries over relational data.
Composer Standard Edition
Composer provides a comprehensive set of features to cover the whole life cycle of semantic application development. In addition to being a complete ontology editor with refactoring support, Composer also can be used as a run-time environment to execute rules, queries, reasoners and mash-ups. Beside SPARQL Rules (SPIN), the Standard Edition also supports other inference engines including Jena rules, SwiftOWLIM and Pellet.
Maestro Edition
TopBraid Composer Maestro Edition (TBC-ME) is the most comprehensive version of TopBraid Composer. It is optimized for developing web applications and services based on the TopBraid Live platform.
TBC-ME can be used to develop and execute SPARQLMotion scripts including web services for processing data chains and creating integrated data services. TBC-ME includes its own internal web server for testing applications resulting in significantly improved turn-around times in application development. TBC can also be used to run TopBraid Ensemble and assemble Ensemble-based applications. To run TopBraid Ensemble out-of-the-box within TBC-ME, open a web browser and go to http://localhost:8083/tbl/