Table of Contents:

Contents

Semantic Web Development Tools: Introduction
General Development Environments, Editors, Content Management Systems, ...
RDF Triple Store Systems
Programming Environments
OWL Reasoners
RDF Generators
On-line Validators
SPARQL "Endpoints"
Special Browsers
1. RDF and/or OWL Browsers
2. Semantic Web Browsers
Search Engines
Tools for Converting Classifications and Other KOS into RDF-S or OWL Ontologies
Tagging and Semantic Web Vocabularies

Semantic Web Development Tools: Introduction

This page contains the information on RDF and OWL tools that used to be listed on the home pages of the RDF and OWL Working Groups at W3C. Keeping such lists up-to-date is obviously a problem when the number of Semantic Web tools increases every day. By moving this list to the Wiki, we hope that the community at large will help maintain these pages (see also notes for contributors).

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:

Sweet Tools maintained by Michael K. Bergman
list at the Freie Universität Berlin, maintained by Chris Bizer and Daniel Westphal
comprehensive list of SW tools and systems is maintained at the SemanticWeb.gr Wiki.
The W3C Multimedia Semantics Incubator Group maintains the list of tools and resources relevant to multimedia semantics.

There are also separate pages maintained on this Wiki for:

SPARQL implementations, set up by the SPARQL Working Group (although most of the information is present on this page, too)
SPARQL "endpoints", examples of using SPARQL in exposing various data. Some of those also accept references to external data; these are also listed below.
"RDF Path" languages, ie, languages and template languages are used to transform RDF triples (or graphs) into another form, typically a web interface in HTML
Tools binding RDF and SQL
Large triple stores
A separate page on commercial products, giving more information and details on some of the entries listed on this page
List of converter tools, converting various format of data to RDF; and its counterpart, another list of converter tools, coverting from RDF to various formats.
Custom RDF dialects, ie various XML dialects or Microformats that have an agreed-upon GRDDL service to convert into RDF

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: 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: Altova's SemanticWorks 2006 is a visual RDF/OWL editor from the creators of XMLSpy. See additional info
Amilcare: University of Sheffield's Amilcare is an adaptive Information Extraction tool designed to support document annotation for the Semantic Web
Arity's LexiLink: 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: 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: 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
CMap COE: 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: 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.
DERI Ontology Management Environment (DOME): DOME comprises tool support for Editing & Browsing, Versioning & Evolution, as well as Mapping & Merging, offered in the form of freely combinable Eclipse Plug-ins.
Graphl: Graphl is a tool for collaborative editing and visualisation of RDF graphs.
GrOWL: GrOWL provides a graphical browser and an editor of OWL ontologies that can be used stand-alone or embedded in a web browser.
IBM's IODT: IODT, IBM's toolkit for ontology-driven development. See additional info
IBM's Web Ontology Manager: IBM's Web Ontology Manager is a lightweight, Web-based tool for managing ontologies expressed in Web Ontology Language (OWL).
IBM Semantic Layered Research Platform: 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: Intellidimension's RDF InferEd is a powerful authoring environment that gives you the ability to navigate and edit RDF (Resource Description Framework) documents
IsaViz: 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: Knoodl is sort of an ontology editor, registry/repository, and wiki all rolled into an easy to use online application.
Language & Computing's LinKFactory: 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.
Metatomix M3t4.Studio Semantic Toolkit: The M3t4.Studio Semantic Toolkit is a free set of Eclipse plugins to allow developers to create and manage OWL ontologies and RDF documents.
Model Futures OWL Editor: 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.
oBrowse: 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.
OntoStudio: OntoStudio is a professional developing environment for ontology-based solutions. It combines modelling 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: 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's Data Spaces Platform: 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: OWL verbalizer is an on-line tool that verbalizes OWL ontologies in (controlled) English
OwlSight: 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: pOWL delivers a PHP and web-based ontology editing and management solution
Profium's Semantic Information Router: 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
Protégé: 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. Examles 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 backends 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-Gravity: RDF Graph Visualization tool
RDFe: RDFe is a Schema-Aware RDF Editor, based on pyrple.
Sandpiper Software's Visual Ontology Modeler: 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.
Semantic Web Client: 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: 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: 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: 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 Snoggle turns these mappings into SWRL/RDF or SWRL/XML for use in a knowledge base.
Software AG's Enterprise Information Integrator (EII): 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
SWIC: 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: SWOOP from the University of Maryland is a A Hypermedia-based Featherweight OWL Ontology Editor
Talis Platform: 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 DannyAyers for details.
Teranode's Experiment Design Automation: 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 Publisher: 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
Top Quandrant's TopBraid Composer: Top Quandrant's TopBraid Composer is a complete standards-based platform for developing, testing and maintaining Semantic Web applications. The tool also implements RDFa and GRDDL. See additional info
VisualKii: 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.
VisualKnowledge: 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: @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.

Aduna Metadata Server: 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 server.
ARC Store: ARC's RDF store supports SPARQL, write operations, and SPARQL Protocol HTTP bindings. (ARC is open source and written in PHP)
Boca: 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).
D2RQ and D2R Server: 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.
Dojo Data: Dojo.data is a Dojo javascript module that includes an rdf data store (dojo.data.RdfStore).
Franz Inc's AllegroGraph: 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: Intellidimension's RDF Gateway is an RDF Triple database with RDFS reasoning and SPARQL interface
Jena SDB: 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)
Kowari: 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.
Mulgara: 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.
OpenLink Virtuoso: Virtuoso 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: 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.
OWLIM: OWLIM is a high-performance semantic repository, packaged as a Storage and Inference Layer (SAIL) for the Sesame RDF database. See additional info
Pubby: Pubby is an RDF server that adds a Linked Data interface to existing SPARQL-capable triple stores.
RDFStore: RDFStore is an RDF storage with Perl and C API-s and SPARQL facilities
RAP's RDF server: The RDF server of the PHP RAP environment.
Semantic Server: 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 for .NET: SemWeb supports persistent storage in MySQL, Postgre, and Sqlite; has been tested with 10-50 million triples; supports SPARQL.
Sesame: Sesame is a Java framework that is also a triple store; (see also the entry on Sesame).
SDB: SDB is a SPARQL database subsystem for Jena. It provides for large scale storage and query of RDF datasets using conventional SQL databases. The database tools for load balancing, security, clustering, backup and administration can all be used to manage the installation.
SWI-Prolog Semantic Web Server: The SWI-Prolog Semantic Web Server implements SPARQL and SeRQL on top of the SWI-Prolog Semantic Web library.
Talis Platform: 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 DannyAyers for details.
Tucana Suite: Northrop Grumman's Tucana Suite is an industrial quality version of the Kowari Metastore.
YARS: 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: 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

Programming Environments

Multilanguage environments

Euler: 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.
Redland RDF Application Framework: 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: Corese 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: DartGrid is an java-based application development framework for integrating heterogeneous relational databases using semantic web technologies.
Internet Business Logic Service Oriented Architecture Endpoint: An advanced rule writing and processing endpoint on the Web You can write and test executable English rules using a browser pointed to http://www.reengineeringllc.com. Then you can extend this Java client endpoint stub to make your rules available in your Service Oriented Architecure. 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: 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: JRDF Java RDF Binding is an attempt to create a standard set of APIs and base implementations to RDF using Java.
OWLJessKB: 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.
RDFSuite: ICS-FORTH RDFSuite 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).
YARS: 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.
Sesame: 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: RDF Entity Manager provides a Java persistence framework using semantic annotations to save objects to the Sesame RDF store.

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

Python Developers

CWM: 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: pyrple parses RDF/XML, N3, and N-Triples. It has in-memory storage with API-level querying, experimental marshalling, many utilities, and is small and minimally interdependent. It can do graph isomorphism testing, rule application, etc.
RDFLib: RDFLib, an RDF libary for Python, including a SPARQL API. The library also contains both in-memory and persistent Graph backends.
SPARQL endpoint interface for Python: 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: 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.
4Suite 4RDF: The 4Suite 4RDF an open-source platform for XML and RDF processing implemented in Python with C extensions.
pySesame: pySesame is a Python wrapper around the Sesame framework.
pysparql: pysparql is an interface to access SPARQL endpoints via HTTP GET
rdfxml.py: rdfxml.py is a standalone Python module in under 10KB that parses RDF/XML using SAX.
RDFSClosure: RDFSClosure is a brute force implementation of the RDFS semantics on the top of RDFLib. It also implements the pD* semantics (also known as "ter Horst Semantics").

See also the Euler engine and the Redland Framework.

C Developers

See RDFStore and the Redland Framework[#redland ]

C++ Developers

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

Javascript Developers

AJAX Client for SPARQL: 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
Dojo Data: Dojo.data is a Dojo javascript module that includes an rdf data store (dojo.data.RdfStore).
Javascript RDF/Turtle parser: Javascript RDF/Turtle parser, can be used with Jibbering
Jibbering: Jibbering, a simple javascript RDF Parser and query thingy
RDFParser: RDFParser is fully compliant with RDF/XML and is usable with browsers implementing DOM Level 2
SPARQL JavaScript Library: SPARQL JavaScript Library interfaces to the SPARQL Protocol and interpret the return values as part of an AJAX framework.

Tcl/Tk Developers

See also the Redland Framework

PHP Developers

Triplify: http://triplify.org 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.
ARC: 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: 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

See also the Redland Framework

Lisp Developers

Wilbur: 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: 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: SWI-Prolog is a comprehensive Prolog environment, which also includes an RDF Triple store.
Thea: 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 AllgroGraph system

Perl Developers

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

See RDFStore and the Redland Framework

Ruby Developers

ActiveRDF: 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: Rena is being reformulated by Tom Morris.
RDF.rb: RDF.rb is an RDF project for Ruby by Arto Bendiken.

See also the Redland Framework

Haskell Developers

Swish: Swish is a framework for performing deductions in RDF. It has similar features to CWM.
Weso: Weso is a set of semantic web tools developed as part of a Declarative Programming course at the University of Oviedo.

OWL Reasoners

Bossam: Bossam, a rule-based OWL reasoner (free, well-documented, closed-source).
FaCT++: FaCT++ is an OWL DL Reasoner implemented in C++
KAON2: KAON2 is an 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.
Pellet: 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.
RacerPro: RacerPro is an OWL reasoner and inference server for the Semantic Web

RDF Generators

Cypher: Cypher Generates RDF and SPARQL/SeRQL representation of natural language statements and phrases
FOAF-o-matic: FOAF-o-matic Online FOAF generator
Open Calais: Open Calais from [Reuters http://www.reuters.com] 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.
Triplify: http://triplify.org 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.

On-line Validators

BBN OWL Validator: BBN OWL Validator
OWL Consistency checker: OWL Consistency checker (based on Pellet)
WonderWeb OWL-DL Validator: WonderWeb OWL-DL Validator
W3C's RDF Validator: W3C's RDF Validator
RDF/XML and N3 Validator: rdfabout.com's Validator
VIStology's ConsVISor OWL Consistency checker: ConsVISor

SPARQL "Endpoints"

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

The Semantic Discovery System (SDS): 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)
D2R: D2R Server, turns relational databases into SPARQL endpoints, based on Jena's Joseki
SPARQLer: SPARQLer; see http://sparql.org for a description
SPARQLette: A SPARQL demo query service
OpenLink Virtuoso: Live SPARQL Query Service Endpoint ; see http://demo.openlinksw.com/sparql_demo for additional details and usage samples (including remoting to other SPARQL Query Services).
Talis Platform: 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 browsers (although there might be restrictions).

RDF and/or OWL Browsers

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

BrowseRDF: Faceted browser, based on ruby on rails.
/facet: /facet, a generic faceted browser
Longwell: Longwell, and RDF powered highly-configurable browser
LENA: Lena stands for LEns based NAvigator. A browser that renders RDF based on Fresnel lens descriptions.
OWLSight: 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.
mSpace: mSpace, a faceted browser

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: Disco (primarily server side); developed at the Free University of Berlin, Germany
Marbles: Marbles (primarily server side); developed at the Free University of Berlin, Germany
Objectviewer: primarily server side
OpenLink RDF Browser: primarily server side but with strong AJAX components, set up by OpenLink.
Ripple: 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.
Zitgist RDF Browser: primarily server side; developed at Zitgist LLC.

Search Engines

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

Falcon: Falcon
Sindice: 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: Swoogle lets user-agents search for Semantic Web Documents, especially Semantic Web Ontologies.
SWSE: 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.

See also LOD page on Semantic Web Search Engines.

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

SKOS2GenTax: 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: 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

CategorySwTools CategorySweoDoc