Welkin is a free tool for visualizing complex RDF models offered for download by the SIMILE Project. Rather than permitting users to focus on specific nodes, it provides analytical views such as an overview of a dataset's connectivity or potential mappings between resources and ontologies. It runs best through Java WebStart and is compatible with Windows, OS X and Linux.

RDF Gravity (RDF Graph Visualization Tool) is a free, open-source visualization tool from Salzburg Research's Knowledge Information Systems Group. It supports RDF graph structures and OWL ontologies, including multiple RDF files, and offers a variety of filters for its visualizations.

RDF2SVG is a web-based tool from the Rhizomik initiative for transforming RDF/XML data into an SVG representation. It can also accept N-triples and N3 input, and includes a feature for filtering the user's defined preferred language from the source data.   

The W3C RDF Validation Service is a free, web-based tool for checking RDF documents for errors and displaying the results. It can display in triples, a graph, or a combination of the two, and can format the graph in a variety of file formats including PNG, SVG and GIF. Documents can be pasted directly into the provided form or from a provided URI.

Google Charts (formerly the Google Visualization API) is a web-based interface for interactive data visualization via HTML5 and SVG. It includes a number of preset chart types ranging from line charts to word trees and all are customizable. A separate selection of user community contributed chart types is also available. Within a chart, the API identifies events that users can trigger with presets ranging from simple clicks to Javascript methods, and enable users to construct chart dashboards that can be embedded in their website along with the chart proper.

Importing, transforming, storing and indexing data should be easy.

Catmandu is a command line tool to access and convert data from your digital library, research services or any other open data sets. Catmandu provides a suite of Perl modules to ease the import, storage, retrieval, export and transformation of metadata records. Combine Catmandu modules with web application frameworks such as PSGI/Plack, document stores such as MongoDB and full text indexes such as Solr to create a rapid development environment for digital library services such as institutional repositories and search engines.

In the http://librecat.org/ project it is our goal to provide an open source set of programming components to build up digital libraries services suited to your local needs.

Read an in depth introduction into Catmandu programming at https://github.com/LibreCat/Catmandu/wiki/Introduction.

Exhibit 3.0 is a publishing framework for large scale data-rich interactive Web pages. The beta version is scalable up to 100k items.

Exhibit lets you easily create Web pages with advanced text search and filtering functionalities, with interactive maps, timelines, and other visualizations. The Exhibit 3.0 software has two separate modes: Scripted for building smaller in-browser Exhibits, and Staged for bigger server-based Exhibits.