From Semantic Web Standards

Semantic Web Development Tools: Introduction

This Wiki page is only for programming and development tools. For a more comprehensive information on RDF in general, which also includes articles, descriptions, etc., the reader should refer to Dave Beckett's Resource Description Framework (RDF) Resource Guide.

There are other pages on tool collection, largely overlapping with this, but possibly with a different granularity or emphasis. Some of these are:

There are also separate pages maintained on W3C's ESW Wiki for:

The order in the listings below does not reflect any assessment of the product or tool; simple alphanumeric order is used.

General Development Environments, Editors, Content Management Systems,…

Adobe's XMP is a labeling technology that allows you to embed data about a file, as metadata, into the file itself. See additional info

Altova's SemanticWorks 2006 is a visual RDF/OWL editor from the creators of XMLSpy. See additional info

University of Sheffield's Amilcare is an adaptive Information Extraction tool designed to support document annotation for the Semantic Web

LexiLink is tool for building, curating and managing multiple lexicons and ontologies in one enterprise-wide Web-based application. The core of the technology is based on RDF and OWL.

Asio Designed to address the data volume, variety, and velocity challenge, the Asio Tool Suite supports information discovery via W3C Semantic Web standards and provides for data accessibility via queries posed in a user's own ontology. In addition, the Asio Tool Suite allows systems and users to reach a shared understanding about the meaning, structure, and context of the data exchanged and ensures the user can make a valid decision on the trustworthiness of the data.

Cerebra Server is a technology platform that is used by enterprises to build model-driven applications and highly adaptive information integration infrastructure. See additional info

ClioPatra is an SWI-Prolog for Semantic Web Applications. It joins the SWI-Prolog RDF and HTTP infrastructure with a SeRQL/SPARQL query engine, interfacing to the The Yahoo! User Interface Library (YUI) and libraries that support semantic search. The platform combines a high performance in-core RDF store with flexible reasoning in Prolog, query optimization. Prolog's interactive usage and capabilities of recompiling modified source code while the system remains alive greatly speedup development.

CMap COE is an integrated suite of software tools for constructing, sharing and viewing OWL encoded ontologies based on CmapTools, a concept mapping software used in educational settings, training, and knowledge capturing. Concept maps provide a human-centered interface to display the structure, content, and scope of an ontology.

Cypher generates the RDF graph and SPARQL/SeRQL query representation of a plain language input, allowing users to speak plain language to update and query databases.

disKover is a large scale enterprise RDF content retrevial and visualisation system allowing uses to search over RDF data visualising at a glace intelligence across all triples in the system. (disKover is a commercial product available from Knowledge Now Limited.

DOME comprises tool support for Editing & Browsing, Versioning & Evolution, as well as Mapping & Merging, offered in the form of freely combinable Eclipse Plug-ins.

The Description Logic Complexity Navigator is a web page that allows to review the complexity of reasoning tasks of various description logics by adding or removing features. It includes a comprehensive list of references to the literature.

Eyeball is a 'lint' for RDF. It is a Jena contrib for checking RDF models (including OWL) for common problems. It is user-extensible using plugins.

Graphl is a tool for collaborative editing and visualization of RDF graphs.

GrOWL provides a graphical browser and an editor of OWL ontologies that can be used stand-alone or embedded in a web browser.

Hyena = wiki + database + synchronization (between online and offline version). Hyena can be run either online, as a web application or offline, as a desktop application (an Eclipse plugin). It manages its data as RDF.

IODT, IBM’s toolkit for ontology-driven development. See additional info

IBM's Web Ontology Manager is a lightweight, Web-based tool for managing ontologies expressed in Web Ontology Language (OWL).

IBM SLRP is a family of open-source Semantic Web software components including an enterprise RDF store, query engine, web application framework, RCP development libraries, and more

Intellidimension's RDF InferEd is a powerful authoring environment that gives you the ability to navigate and edit RDF (Resource Description Framework) documents

Internet Business Logic is a kind of Wiki for writing and running database and RDF applications as syllogism-like rules in open vocabulary, executable English. From the rules, the system generates and runs SQL queries that would be too complicated to write reliably by hand, and it explains the results in English at the business or scientific level. Shared use is free.

IsaViz is a visual authoring tool for browsing and authoring RDF models represented as graphs. Developed by Emmanuel Pietriga of INRIA and formerly of W3C and Xerox Research Centre Europe.

Knoodl is sort of an ontology editor, registry/repository, and wiki all rolled into an easy to use online application.

Language & Computing's LinKFactory is an ontology management tool, it provides an effective and user-friendly way to create, maintain and extend extensive multilingual terminology systems and ontologies (English, Spanish, French, etc.). It is designed to build, manage and maintain large, complex, language independent ontologies.

The M3t4.Studio Semantic Toolkit is a free set of Eclipse plugins to allow developers to create and manage OWL ontologies and RDF documents.

The Model Futures OWL Editor is a free tool that is easy to use and install. It offers a simple tree structure user interface and can handle very large OWL files. It also has XMI, Thesaurus Descriptor, and ErWin(TM) import capabilities, and can export ontologies as MS Word(TM) documents.

myontology is a web tool for browsing and authoring ontologies. The tool is aimed at the process of community engineered ontologies.

The NeOn Toolkit is the ontology development environment developed by the NeOn Project. It focuses on providing support for the complete life cycle of networked ontologies.

oBrowse is a web based ontology browser developed in java. oBrowse parses OWL files of an ontology and displays ontology in a tree view. Protege-API, JSF are used in development.

The TONES Ontology Repository is a web service designed to be a central location for ontologies that might be of use to tools developers for testing purposes. It includes various metrics for the contained ontologies, such as DL expressivity and the number of different axioms.

OntoStudio is a professional developing environment for ontology-based solutions. It combines modeling tools for ontologies and rules with components for the integration of heterogeneous data sources. As ontology-languages OntoStudio supports W3C-standards OWL and RDF(S) and F-Logic for the logic-based processing of rules.

Open Anzo Anzo is an open source enterprise-featured RDF store and middleware platform that provides support for multiple users, distributed clients, offline work, real-time notification, named-graph modularization, versioning, access controls, and transactions with preconditions.

OpenLink Data Spaces (ODS) is a distributed collaborative application platform for creating Semantic Web presence in conjunction with Web 2.0 application profiles such as: Weblogs, Wikis, Feed Aggregators, Bookmark Mangers, Discussion Forums, Photo Galleries, Social Networks, and more. It provides transparent access to application data via in-built SPARQL support and incorporation of shared ontologies such as SIOC, FOAF, and Atom OWL. ODS is an application of OpenLink Virtuoso, and is available in Open Source and Commercial Editions.

OWL verbalizer is an on-line tool that verbalizes OWL ontologies in (controlled) English

OwlSight is an OWL ontology browser that runs in any modern web browser; it's developed with Google Web Toolkit. OwlSight is the client component and uses Pellet as its OWL reasoner.

pOWL delivers a PHP and web-based ontology editing and management solution

Profium's Semantic Information Router (SIR) is a content management system using standardized metadata which improves information reusability and allows the user to process and distribute further information acquired from numerous sources in different formats. See additional info

Stanford University's general Protégé 2000 ontology editor tool has a plugin architecture that allowed the development of a number of Semantic Web related tools. Examples are an OWL plugin (called Protégé-OWL) to edit RDF and OWL ontologies as well as SWRL rules, a visual editor for OWL (called OWLViz), storage back-ends to Jena and Sesame, as well as an OWL-S plugin, which provides some specialized capabilities for editing OWL-S descriptions of Web services.

RDF Graph Visualization tool

RDFe is a Schema-Aware RDF Editor, based on pyrple

Rej is a graphical utility that allows you to write RDF statements directly, using a simple layout that is designed to naturally reflect the basic RDF model.

The VOM family of tools enables UML-based visual construction of component-based ontologies for use in collaborative applications and interoperability solutions. Additional information is available here.

The Semantic Web Client Library represents the complete Semantic Web as a single RDF graph. The library enables applications to query this global graph using SPARQL. To answer queries, the library dynamically retrieves information from the Semantic Web by dereferencing HTTP URIs and by following rdfs:seeAlso links. The library is written in Java and is based on the Jena framework.

Semantic Studio is an ontology development tool of Semantic Soft which stores the ontology in a semantic repository, a database or filesystem of any platform. Development can be done in various modes, including design, graphics, or source mode.

Siderean's Seamark Navigator provides a powerful view of all the information in your enterprise to your users or customers. Web search pages can be combined with product catalog databases, document servers, and other digital information from both inside and outside the enterprise. It also has SPARQL API to get to the data directly.

Snoogle is a graphical, SWRL-based ontology mapper to assist in the task of OWL ontology alignment. It allows users to visualize ontologies and then draw mappings from one to another on a graphical canvas. Users draw mappings as they see them in their head, and then Snoogle turns these mappings into SWRL/RDF or SWRL/XML for use in a knowledge base.

EII version 2.1 is a globally available information integration product that uses Semantic Web technology. By dynamically combining the meaning and context of business data with the rules that govern its use, Enterprise Information Integrator provides business leaders with the resources to make faster decisions based on real time information availability. See the company press release for additional info

SuperModel is a Protégé plugin that is being developed with the goal to present the user with possible Models for concepts of ontologies (and that's Super, of course).

The SWI Semantic Web Client from the Centre for Digital Music is an implementation of a linked data client, looking programmatically for particular information on the Semantic Web. It also embeds a small SPARQL client, allowing to query a pool of SPARQL end-points. This program is built on top of SWI-Prolog.

SWOOP from the University of Maryland is a A Hypermedia-based Featherweight OWL Ontology Editor

The Talis Platform is a hosted data service providing content and triple storage, along with various auxiliary services including change management, access control, index/search and SPARQL. Access is entirely over HTTP (i.e. programming language agnostic). Free use for non-commercial projects, currently in an Early Access beta phase - see N-Squared Wiki, contact Danny Ayers for details.

Teranode's Experiment Design Automation (XDA) software is a powerful platform that allows scientists to automate lab and in-silico experiments and manage data within and across laboratories, to improve the speed and quality of R&D projects.

Thetus provides knowledge discovery and modeling infrastructure software that enables organizations to describe, structure, search, relate, model, share, and re-use information-independent of schema or device. See additional info

TopQuadrant’s TopBraid Suite is a complete standards-based platform for developing, testing and deploying Semantic Web applications. The Suite consists of TopBraid Composer (a data integration toolkit and ontology editor) and TopBraid Live (an application deployment platform with a Flex-based user interface API). The tools also implements RDFa and GRDDL. See additional info

VectorC's Semantic Service Bus (SSB) is a Semantic Web runtime framework based on an enterprise service bus (ESB) architecture. The SSB can query, transform, route and perform reasoning over RDF data and associated ontologies. The underlying MuleSource ESB platform includes a rich set of transports that support integration with data drawn from both RDF and non-RDF sources. The SSB is built on open source components, including the MuleSource ESB, the Spring Framework, the Jena Framework and the Sesame Framework.

VisualKii is a multi-purpose visual programming platform based on Java. It has libraries for processing RDF, N3 and N-TRIPLES models by visually defining data flow and arranging processing steps. It also includes support for SPARQL queries.

Visual Knowledge is a fully integrated Web 3.0 development and execution platform for building semantic sites, semantic wikis, semantic blogs and high performance knowledge-driven applications. The products are fully W3C Standards compliant (OWL, RDF, etc).

@Semantics Enterprise Information Integration (EII) is a federated approach to data management. The EII approach rely fully on open standards, using RDF/S for describing information

RDF Triple Store Systems

See also the separate Wiki page on SPARQL implementations, as well as the the quote page on large triple stores for further information.

4store is a RDF/SPARQL store written in C, it runs on UNIX platforms, either single machines or networked clusters. 4store was developed by Garlik to support their online products.

The Aduna Metadata Server automatically extracts metadata from information sources, like a file server, an intranet or public web sites. The Aduna Metadata Server is a powerful and scalable store for metadata. The Metadata Server is based on the [#sesame Sesame] server.

ARC's RDF store supports SPARQL, write operations, and SPARQL Protocol HTTP bindings. (ARC is open source and written in PHP)

Boca enterprise RDF store is a Java-based store and client libraries which features named-graph-based RDF storage, access controls, versioning, replication and local persistence for offline access, and notifications (eventing) to distributed clients. Boca is part of IBM Semantic Layered Research Platform (SLRP).

disKover is an enterprise RDF search frontEnd capable of storing large scale RDF and semantic data for search and user exploration in a variety of modalities. (disKover is a commercial product offered by K-Now.

D2RQ is a Java library that provides access to the content of relational databases through SPARQL, the Jena API, and the Sesame API. D2R Server is a SPARQL and RDF server based on D2RQ. is a Dojo JavaScript module that includes an RDF data store (

AllegroGraph is a system to load, store and query RDF data. It includes a SPARQL interface and RDFS reasoning. It has a Java and a Prolog interface.

Intellidimension's RDF Gateway is an RDF Triple database with RDFS reasoning and SPARQL interface

Jena's SDB layer offers an RDF Triple Store facility with SPARQL interface on top of other database systems (see also the entry on Jena)

The Kowari Metastore is an Open Source, massively scalable, transaction-safe, purpose-built database for the storage and retrieval of RDF, written in Java. Kowari has not been maintained since December, 2005. See Mulgara for an active fork.

The Mulgara Semantic Store is an Open Source, massively scalable, transaction-safe, purpose-built database for the storage and retrieval of RDF, written in Java. It is an active fork of Kowari.

Virtuoso is a SQL-ORDBMS and Web Application Server hybrid (aka Universal Sever) that provides SQL, XML, and RDF data management in a single multithreaded server process. Triple Store access is available via: SPARQL, SIMILE Semantic Bank API, ODBC, GRDDL, JDBC, ADO.NET, XMLA, WebDAV, and Virtuoso/PL (SQL Stored Procedure Language). The product is available in Open Source and Commercial editions.

Oracle Spatial 11g includes an open, scalable, secure and reliable RDF management platform. Based on a graph data model, RDF triples are persisted, indexed and queried, similar to other object-relational data types. The system also implements subsets of OWL Full.

GraphDB is a high-performance semantic repository, packaged as a Storage and Inference Layer (SAIL) for the Sesame RDF database. See additional info

Pubby is an RDF server that adds a Linked Data interface to existing SPARQL-capable triple stores.

RDFStore is an RDF storage with Perl and C API-s and SPARQL facilities

The RDF server of the PHP RAP environment.

Semantic Server, built by Semantic Soft, stores information in multiple semantic repositories with strong meta-data management features, offers features for collaborative development with security and user management, publishes content from repositories on the web, and has a visual SPARQL processor

SemWeb supports persistent storage in MySQL, PostgreSQL, and SQLite; has been tested with 10-50 million triples; supports SPARQL.

Sesame is a Java framework that is also a triple store; (see also the entry on Sesame).

SDB is a SPARQL database subsystem for Jena. It provides for large scale storage and query of RDF data sets using conventional SQL databases. The database tools for load balancing, security, clustering, backup and administration can all be used to manage the installation.

The SWI-Prolog Semantic Web Server implements SPARQL and SeRQL on top of the SWI-Prolog Semantic Web library.

The Talis Platform is a hosted data service providing content and triple storage, along with various auxiliary services including change management, access control, index/search and SPARQL. Access is entirely over HTTP (i.e. programming language agnostic). Free use for non-commercial projects, currently in an Early Access beta phase - see N-Squared Wiki, contact Danny Ayers for details.

Northrop Grumman's Tucana Suite is an industrial quality version of the Kowari Metastore.

YARS (Yet Another RDF Store) is a data store for RDF in Java and allows for querying RDF based on a declarative query language, which offers a somewhat higher abstraction layer than the APIs.

3Store is a MySQL based triple store. The server software itself does not expose any interfaces directly to the user, but it can be queried by a number of services, including a column based view and a direct RDF browser

Bigdata® is a horizontally-scaled, general purpose storage and computing fabric for ordered data (B+Trees), designed to operate on either a single server or a cluster of commodity hardware. Bigdata® uses dynamically partitioned key-range shards in order to remove any realistic scaling limits - in principle, bigdata® may be deployed on 10s, 100s, or even thousands of machines and new capacity may be added incrementally without requiring the full reload of all data. The bigdata® RDF database supports RDFS and OWL Lite reasoning, high-level query (SPARQL), and datum level provenance. (Open source. Support and commercial licensing available on request.)

Programming Environments

Multi-language environments

Euler is an inference engine supporting logic based proofs. It is a backward-chaining reasoner enhanced with Euler path detection. It has implementations in Java, C#, Python, JavaScript and Prolog. Via N3 it is interoperable with W3C Cwm.

The Redland RDF Application Framework is a set of free software libraries that provide support for RDF. It provides parser for RDF/XML, Turtle, N-triples, Atom, RSS; has a SPARQL and GRDDL implementation, and has language interfaces to C#, Python, Obj-C, Perl, PHP, Ruby, Java and Tcl

Java Developers

Corese stands for Conceptual Resource Search Engine. It is an RDF engine based on Conceptual Graphs (CG). It enables the processing of RDF Schema and RDF statements within the CG formalism, provides a rule engine and a query engine accepting the SPARQL syntax.

DartGrid is an java-based application development framework for integrating heterogeneous relational databases using semantic web technologies.

iblClient] is an advanced rule writing and processing endpoint on the Web] You can write and test executable English rules using a browser pointed to [1]. Then you can extend this Java client endpoint stub to make your rules available in your Service Oriented Architecture. You can use your rules to automatically generate and run complex SQL over networked databases, e.g. containing RDF triples, with explanations in English, at the business or scientific level.

Jena Java RDF API and toolkit is a Java framework to construct Semantic Web Applications. It provides a programmatic environment for RDF, RDFS and OWL, SPARQL, GRDDL, and includes a rule-based inference engine. It also has the ability to be used as an RDF database via its Joseki layer. See the Jena discussion list for more information.

JRDF Java RDF Binding is an attempt to create a standard set of APIs and base implementations to RDF using Java.

OWLJessKB is a description logic reasoner for OWL. The semantics of the language is implemented using Jess, the Java Expert System Shell. Currently most of the common features of OWL Lite, plus some and minus some.

The OWL API is a Java interface and implementation for OWL.

ICS-FORTH RDFSuite is an open source, high-level scalable tools for the Semantic Web. This suite includes Validating RDF Parser (VRP), a RDF Schema Specific DataBase (RSSDB) and supporting RDF Query Language (RQL).

Sesame is an open source RDF database with support for RDF Schema inferencing and querying. It offers a large scale of tools to developers to leverage the power of RDF and RDF Schema. It is a Java framework, there is also a python wrapper.

RDF Entity Manager provides a Java persistence framework using semantic annotations to save objects to the Sesame RDF store.

YARS (Yet Another RDF Store) is a data store for RDF in Java and allows for querying RDF based on a declarative query language, which offers a somewhat higher abstraction layer than the APIs of RDF toolkits such as Jena or Redland.

See also the kowari and allegro systems, and the Euler engine

Python Developers

The 4Suite 4RDF an open-source platform for XML and RDF processing implemented in Python with C extensions.

Closed World Machine (CWM) data manipulator, rules processor and query system mostly using using the Notation 3 textual RDF syntax. It also has an incomplete OWL Full and a SPARQL access

pyrple parses RDF/XML, N3, and N-Triples. It has in-memory storage with API-level querying, experimental marshaling, many utilities, and is small and minimally interdependent. It can do graph isomorphism testing, rule application, etc.

pySesame is a Python wrapper around the Sesame framework.

pysparql is an interface to access SPARQL endpoints via HTTP GET

RDFLib is an RDF library for Python, including a SPARQL implentation. The library also contains both in-memory and persistent Graph back-ends.

OWL RL Service is a brute force implementation of the RDFS and OWL 2 RL semantics on the top of RDFLib. The the software is also downloadable and the library usable as a Python module. is a standalone Python module in under 10KB that parses RDF/XML using SAX.

SPARQL Endpoint interface to Python. The goal is to give some help in turning a SPARQL query into the corresponding HTTP GET Protocol, send it to a SPARQL endpoint somewhere on the Web, and do something with the results.

Sparta is an Python API for RDF that is designed to help easily learn and navigate the Semantic Web programmatically. Unlike other RDF interfaces, which are generally triple-based, Sparta binds RDF nodes to Python objects and RDF arcs to attributes of those Python objects.

See also the Euler engine and the Redland Framework, as well as the allegro system.

C Developers

See RDFStore and the Redland Framework

C++ Developers

Brahms is a fast main-memory RDF/S storage, capable of storing, accessing and querying large ontologies. It is implemented as a set of C++ classes

C# and .Net Developers

Drive is an RDF parser written in C# for the .NET platform.

ROWLEX is a .NET library and toolkit built to create and browse RDF documents easily. It abstracts away the level of RDF triples and elevates the level of the programming work to (OWL) classes and properties.

SemWeb is an RDF library in C# with persistent RDBMS storage, XML and N3 reading/writing, SPARQL, and RDFS inferencing

See also the Euler engine and the Redland Framework

Flex/ActionScript Developers

TopBraid Live Flex API is a client-side RDF API with an automated client-server caching and synchronization mechanism as well as a client-side query and rule engine. TopBraid Live also provides an extensive library of reusable model-driven components in Flex such as maps, graphs, forms and query editors.

SemanticFlash is an open source ActionScript 3 Semantic Web framework. Currently under development, it will provide a standard i/o stack ( parsers, network ), native bindings for RDF scripting and User Interface binding facilities along with basic inference and smushing. It will also aim to provide a lightweight Linked Data Client as a drop-in component to enable the development of Rich Linked Data meshups on Adobe Flex/AIR.

JavaScript Developers

AJAX Client for SPARQL is a simple AJAX client that can be used for running SELECT queries against a service and then integrating them with client-side JavaScript code is a Dojo JavaScript module that includes an RDF data store (

Hercules is a free semantic web framework, contains RDF/XML and Turtle parser and pure JavaScript SPARQL query engine.

JavaScript RDF/Turtle parser, can be used with Jibbering

Jibbering, a simple JavaScript RDF Parser and query thingy

OpenLink AJAX Toolkit (OAT) is an AJAX Framework, components of which were used to implement the OpenLink Data Explorer (ODE) (evolved from the OpenLink RDF Browser and OpenLink RDF Browser 2), and the iSPARQL Interactive SPARQL Query Builder. The included Form Designer permits easy construction of other Browser-based RDF and SPARQL tools.

RDFParser is fully compliant with RDF/XML and is usable with browsers implementing DOM Level 2

SPARQL JavaScript Library interfaces to the SPARQL Protocol and interpret the return values as part of an AJAX framework.

See also the Euler engine

Tcl/Tk Developers

See also the Redland Framework

PHP Developers

ARC is “a flexible RDF system for semantic web and PHP practitioners. It's open-source, easy to use, and runs in most web server environments”.

RAP is a pure PHP package for manipulating RDF models and parsing/serializing the RDF/XML syntax. It includes an integrated RDF/XML, n3, n-triple, TriX, GRDDL, and RSS parser, a SPARQL query engine and SPARQL client library and an integrated RDF server

Triplify is a small plugin for Web applications, which reveals the semantic structures encoded in relational databases by making database content available as RDF, JSON or Linked Data.

See also the Redland Framework

Lisp Developers

Wilbur is lisp based toolkit for Semantic Web Programming. Wilbur is Nokia Research Center's toolkit for programming Semantic Web applications that use RDF written in Common Lisp.

Obj-C Developers

See also the Redland Framework

Prolog Developers

dlpconvert is a tool for the conversion of the Horn fragment of OWL (called DLP) from XML or RDF syntax to Prolog syntax (see also Kaon2)

SWI-Prolog is a comprehensive Prolog environment, which also includes an RDF Triple store. See also the CliPatria system for a more complete system based on SWI-Prolog.

Thea OWL library is a Prolog implementation of an OWL library. Thea also has a reasoning module with an OWL to Prolog converter and a Prolog to DIG wrapper for interfacing with a DIG reasoner.

See also the Euler engine and the AllegroGraph system

Perl Developers

CARA is an RDF API written in Perl. CARA is based on the graph model of RDF and supports in-memory and persistent storage of RDF graphs. An RDF Parser is included in the API.

RDF::Query is a RDF query implementation of SPARQL/RDQL.

RDF::Helper provide a consistent, Perl-ish interface to Perl's various RDF processing tools.

See RDFStore and the Redland Framework

Ruby Developers

ActiveRDF is a library for accessing RDF data from Ruby programs. It can be used as data layer in Ruby-on-Rails. You can address RDF resources, classes, properties, etc. programmatically, without queries.

Rena is being reformulated by Tom Morris.

RDF.rb is an RDF project for Ruby by Arto Bendiken.

See also the Redland Framework

Haskell Developers

Swish is a framework for performing deductions in RDF. It has similar features to CWM.

Weso is a set of semantic web tools developed as part of a Declarative Programming course at the University of Oviedo.

Reasoners (OWL or rule based) and related tools

BaseVISor is a forward-chaining inference engine specialized to handle facts in the form of RDF triples with support for RuleML, R-Entailment and XML Schema Datatypes. BaseVISor is a Java application and API.

Bossam, a rule-based OWL reasoner (free, well-documented, closed-source).

FaCT++ is an OWL DL Reasoner implemented in C++

Graal is a Java toolkit dedicated to querying knowledge bases within the framework of existential rules, aka Datalog+/-. Graal provides a translator from OWL to DLGP (Datalog+ concrete syntax).

KAON2 is an infrastructure for managing OWL-DL, SWRL, and F-Logic ontologies. it is capable of manipulating OWL-DL ontologies; queries can be formulated using SPARQL.

OpenLink Virtuoso (elsewhere on this page) is also an OWL Reasoner. As of this writing, it supports owl:sameAs, rdfs:subClassOf, and rdfs:subPropertyOf, which are sufficient for many purposes. As of 5.00.3031, owl:sameAs, owl:equivalentClass, and owl:equivalentProperty are also considered when determining subclass or subproperty relations. Virtuoso defaults to using backward-chaining, but if desired, forward-chaining (i.e., materialized inferences) may be forced.

OWL RL Service is a brute force implementation of the RDFS and OWL 2 RL semantics on the top of RDFLib. The the software is also downloadable and the library usable as a Python module.

Pellet is an open-source Java based OWL DL reasoner. It can be used in conjunction with both Jena and OWL API libraries; it can also be downloaded and be included in other applications.

Pellint is an open source lint tool for Pellet which flags and (optionally) repairs modeling constructs that are known to cause performance problems. Pellint recognizes several patterns at both the axiom and ontology level.

RacerPro is an OWL reasoner and inference server for the Semantic Web

SHER is an ontology analytics and reasoning engine that scales to very large and expressive RDF/OWL knowledge bases stored in a relational database.

See also the Euler engine, AllegroGraph, Oracle, GraphDB or Jena. Furthermore, Uli Sattler maintains a list of Description Logic reasoners.

Modularization and diffing tools

CEX (pronounce: keks) is a CAML-based implementation of determining the logical difference between two given EL-terminologies (for instance, SNOMED CT) as described in "Logical Difference and Module Extraction with CEX and MEX".

MEX is a CAML-based implementation of extracting a semantic module from a given acyclic ELI-terminology (for instance, SNOMED CT) as described in "Logical Difference and Module Extraction with CEX and MEX".

The OWL Module Extractor is a web service that extracts a module for a given set of terms from an ontology. It is based on an implementation of locality-based modules that is part of the OWL API.

SegmentationApp is a Java application that segments a given ontology according to the approach described in "Web Ontology Segmentation: Analysis, Classification and Use".

RDF Generators

Cypher Generates RDF and SPARQL/SeRQL representation of natural language statements and phrases

FOAF-o-matic Online FOAF generator

inqle: Intelligent network of Querying and Learning Engines. Open Source server, with Jena SDB back-end datastore. Runs automated, random machine learning experiments on semantic data. Stores any discovered correlations as RDF, and leverages such correlations in performing future experiments. Provides tools for loading spreadsheet data into the RDF database.

Krextor is a framework for extracting RDF from various XML languages (see a separate page for details)

Ontos API is a public web service which returns rich semantic metadata in standard RDF-based formats for input plain text content you submit. Ontos recognizes entities and relations between them using natural language processing techniques. Although basic types of entities (people, companies, places etc.) are pre-defined, the user can also create OWL-driven dictionaries for custom types of entities, merge entities across documents, etc. For more details, tips and updates see Ontos API home, the official blog, and the community group.

Open Calais from [Reuters] is a web service that automatically attaches rich semantic metadata to the content you submit. Using natural language processing, machine learning and other methods, Calais categorizes and links your document with entities (people, places, organizations, etc.), facts (person ‘x’ works for company ‘y’), and events (person ‘z’ was appointed chairman of company ‘y’ on date ‘x’). The metadata results are stored centrally and returned as RDF constructs.

OpenLink Virtuoso (elsewhere on this page) delivers SQL2RDF directly, and via the Sponger and its cartridges, also delivers RDF from GRDDL, RDFa, microformats, and many more inputs.

pyRdfa, a downloadable Python package as well as online service to generate RDF from RDFa pages

Semantic Hacker's technology provide a weighted representation of the concepts contained in a piece of text. (It does not provide RDF directly yet...)

Triplify is a small plugin for Web applications, which reveals the semantic structures encoded in relational databases by making database content available as RDF, JSON or Linked Data.

Zemanta API is a web API that delivers relevant tags, links, categories and pictures from your unstructured data/content. It is semantic standards compliant, with RDF output and ability to disambiguate to entities from Linking Open Data.

Twarql is an open source Java implementation of the Linked Open Social Signals architecture. Twarql reads streams of tweets, extracts information such as URLs, named entities and hashtags, encodes them in RDF and filters streaming information using SPARQL queries. The information matching the queries is then published using sparqlPuSH.

On-line Validators

BBN OWL Validator

Ontology Metrics is a web-based tool that displays statistics about a given ontology, including the expressivity of the language it is written in.

OWL Consistency checker (based on Pellet)'s Validator

Vapour is a linked data validator. It checks, for example, for meaningful triples in the response documents, links to popular semantic web browsers, and conclusions on the type of the resources per httpRange-14.


W3C's RDF Validator

WonderWeb OWL-DL Validator

FOAF Validator checks FOAF files for a number of common issues.

SPARQL “Endpoints”

(see also: SPARQL End points, SPARQL implementations pages on the ESW wiki of W3C)

These endpoints offer a URI with a SPARQL service that can be accessed using the SPARQL Protocol spec, and return XML and/or JSON.

D2R Server, turns relational databases into SPARQL endpoints, based on Jena's Joseki

Knoodl is sort of an ontology editor, registry/repository, and wiki all rolled into an easy to use online application. All ontologies store in Knoodl can be exposed as SPARQL Endpoints.

OpenLink Virtuoso ( elsewhere on this page) includes a Live SPARQL Query Service Endpoint in all installations. Includes SPARQL-to-SQL gateway for locally-housed data in both Open-Source and Commercial Edition; Commercial Edition extends SPARQL Query distribution to any ODBC- or JDBC-accessible data sources, SQL-DBMS or otherwise. Additional details and usage samples (including remoting to other SPARQL Query Services) are available.

[ The Semantic Discovery System] SPARQL Query Over Distributed Data (Oracle, any RDBMS, Web Services, Excel, Non Relational Data...) SPARQL Endpoint, Automated Mapping to/from OWL all Connected Data Sources (end Q4 2007)

SPARQLer; see for a description

A SPARQL demo query service

The Talis Platform is a hosted data service which provides SPARQL endpoints, see N-Squared Wiki.

Some of these systems can also be downloaded and installed locally to provide a local SPARQL endpoint.

Special Browsers

Means to directly visualize/explore RDF data. They work in your usual web browsers (although there might be restrictions).

See also: Editing Data page EditingData

RDF and/or OWL Browsers

These can be plugged on top of a local RDF store, can possibly be added to your application, etc,

Faceted browser, based on ruby on rails.

/facet, a generic faceted browser

Ontology Online JavaScript library that loads and visualizes OWL-DL documents client-side.

Knoodl is sort of an ontology editor, registry/repository, and wiki all rolled into an easy to use online application.

Lena stands for LEns based NAvigator. A browser that renders RDF based on Fresnel lens descriptions.

Longwell, and RDF powered highly-configurable browser

mSpace, a faceted browser

Ontology Browser is an ontology browser created as part of the CO-ODE project.

OWLSight is an OWL ontology browser that runs in any modern web browser; it's developed with Google Web Toolkit. OWLSight is the client component and uses Pellet as its OWL reasoner.

TopBraid Ensemble is a Flex-based rich internet application that can be used to browse and edit RDF-based models. Integrated with TopBraid Composer for ontology and form layout design.

Cuebee is a Javascript-based query interface that guides users in building SPARQL queries by interacting with SPARQL endpoints. The results can be displayed in several visualization perspectives.

Scooner: is a Javascript-based browser that pulls triples from SPARQL endpoints to guide the navigation of text documents.

Semantic Web Browsers

These tools usually work without the necessity of a local browser, they retrieve the data on the Web directly, dereferencing the URIs

Disco (primarily server side); developed at the Free University of Berlin, Germany

Marbles (primarily server side); developed at the Free University of Berlin, Germany

Object Viewer, primarily server side OpenLinkDataExplorer Firefox extension with strong AJAX connections to various server-based components, set up by OpenLink. ODE is also available in a Web-server-side form, which does not require the ODE Extension and works with any Web browser, as part of the OpenLink AJAX Toolkit.

fortytwo]: client-side, text-based browser; user queries the Semantic Web at the command line Tabulator]: client side JavaScript based program; developed at the MIT CSAIL lab. As a Firefox add-on, adds data browser/editor functionality to your document browser.

Zitgist primarily server side; developed at Zitgist LLC.

SIOC Browser is a RDF browser written in Python.

Search Engines

These are online search engines specialized in OWL and/or RDF content.


Sindice is a lookup index for Semantic Web documents. Sindice indexes the Semantic Web and can tell you which sources mention a resource URI, IFP, or keyword. Sindice does not answer triple queries. You can use Sindice in your application to find relevant RDF sources.

Swoogle lets user-agents search for Semantic Web Documents, especially Semantic Web Ontologies.

SWSE provides an entity-centric view on Semantic Web instances. SWSE also provides a SPARQL endpoint over currently around 400k RDF files from the Web.

Watson is a Semantic Web gateway. It collects, analyses and indexes semantic documents online, in order to provide advanced access mechanisms and services for developer to build semantic applications that exploit online knowledge on the Semantic Web.

See also LOD page on Semantic Web Search Engines.

Tools for Converting RDF Data between different Serializations

babel: services provided by MIT’s SIMILE project to convert between various formats.

Morph will convert data between different Semantic Web "formats"/RDF serializations. Accepted input formats are Semantic HTML, RDF/XML, RDF/JSON and Turtle, plus SPARQL/XML and Facet XML. Output formats are HTML, JSON and JSONP for all input formats, plus RDF/XML, RSS1.0 Turtle, TriX, Exhibit (HTML), Exhibit JSON and Exhibit JSONP for RDF input. The service will also merge and convert multiple input files. The HTML output gives a basic RDF viewer/browser. Morph was developed by Keith Alexander from Talis.

triplr: RDF format transformations

URIBurner is a simple but power service that delivers RDF based structured descriptions of Web addressable resources (documents or real world objects) in a variety of formats, including but not limited to RDF/XML, Turtle, N3. Also supports hand-written or query-by-example SPARQL querying over linked data (powered by OpenLink Virtuoso).

Tools for Converting Classifications and Other KOS into RDF-S or OWL Ontologies

OWL Syntax Converter is an online tool for converting ontologies between different formats, including several OWL syntaxes, RDF/XML, KRSS.

SKOS2GenTax is an online tool for deriving consistent RDF-S and OWL ontologies from hierarchical classifications provided in the SKOS format.

Tagging and Semantic Web Vocabularies

MOAT (Meaning of a Tag) provides a Semantic Web framework to publish semantically-annotated content from free-tagging. MOAT provides a way for users to define meaning(s) of their tag(s) using URIs of Semantic Web resources (such as URIs from DBpedia, GeoNames … or any knowledge base), and then annotate content with those URIs rather than free-text tags