Coollab is a free, open-source, node-based software for creating generative visuals in real time. It is designed to be very intuitive and easy to use, yet very powerful and flexible!

Patchies is a patcher for things that runs on the web. Patch together audio, visual and computational objects e.g. P5, Hydra, Strudel, ChucK, Orca, Tone.js, GLSL, etc.

Cables is a tool for creating beautiful interactive content. With an easy to navigate interface and real time visuals, it allows for rapid prototyping and fast adjustments.

You are provided with a set of operators, such as mathematical functions, shapes, materials and post processing effects.
Connect these to each other with virtual cables to create the experience you have in mind.
Easily export your piece of work at any time. Embed it into your website or use it for any kind of creative installation.

Audio visualizer library for javascript. Create dynamic animations that react to an audio file or audio stream.

Azimutt is an Entity Relationship Diagram (ERD) targeting real world database schema (big & messy).

Apache Superset is a modern data exploration and visualization platform

Set of tools for livecoding networked visuals. Inspired by analog modular synthesizers, these tools are an exploration into using streaming over the web for routing video sources and outputs in realtime.

Metabase is the easy, open source way for everyone in your company to ask questions and learn from data.

Superset is a data exploration platform designed to be visual, intuitive and interactive.

Superset's main goal is to make it easy to slice, dice and visualize data. It empowers users to perform analytics at the speed of thought.

Superset provides:

A quick way to intuitively visualize datasets by allowing users to create and share interactive dashboards
A rich set of visualizations to analyze your data, as well as a flexible way to extend the capabilities
An extensible, high granularity security model allowing intricate rules on who can access which features, and integration with major authentication providers (database, OpenID, LDAP, OAuth & REMOTE_USER through Flask AppBuiler)
A simple semantic layer, allowing to control how data sources are displayed in the UI, by defining which fields should show up in which dropdown and which aggregation and function (metrics) are made available to the user
Deep integration with Druid allows for Superset to stay blazing fast while slicing and dicing large, realtime datasets
Fast loading dashboards with configurable caching

RAW is an open web tool to create custom vector-based visualizations on top of the amazing d3.js library.

Primarily conceived as a tool for designers and vis geeks, RAW aims at providing a missing link between spreadsheet applications (e.g. Microsoft Excel, Apple Numbers, Google Docs, OpenRefine, …) and vector graphics editors (e.g. Adobe Illustrator, Inkscape, …).

RAW works with tabular data (e.g. spreadhseets and comma-separated values) as well as with copied-and-pasted texts from other applications (e.g. Microsoft Excel, TextWrangler, TextEdit, …). Based on the SVG format, visualizations can be easily edited with vector graphics applications for further refinements, or directly embedded into web pages.

Knowing the need of working with sensitive information, the data uploaded to RAW is processed only by the web browser: no server-side operations or storages are performed and no one will see, touch or copy your data!

Grafana provides a powerful and elegant way to create, explore, and share dashboards and data with your team and the world.

Grafana is most commonly used for visualizing time series data for Internet infrastructure and application analytics but many use it in other domains including industrial sensors, home automation, weather, and process control.

Query Editor: think of JS Fiddle for SQL queries. It's your way to share data in the organization in an open way, by sharing both the dataset and the query that generated it.
Visualizations: once you have a dataset, you can create different visualizations out of it.
Dashboards: combine several visualizations into a single dashboard.

D3.js is a JavaScript library for manipulating documents based on data. D3 helps you bring data to life using HTML, SVG and CSS. D3’s emphasis on web standards gives you the full capabilities of modern browsers without tying yourself to a proprietary framework, combining powerful visualization components and a data-driven approach to DOM manipulation.

dancer.js is a high-level audio API, usable with both Mozilla's Audio Data API and Webkit's Web Audio API with flash fallback, designed to make sweet visualizations.

Beautifully crafted timelines that are easy, and intuitive to use.

TileMill is an application for making beautiful maps

The Visual Understanding Environment (VUE) is an Open Source project based at Tufts University. The VUE project is focused on creating flexible tools for managing and integrating digital resources in support of teaching, learning and research. VUE provides a flexible visual environment for structuring, presenting, and sharing digital information.

Processing.js is the sister project of the popular Processing visual programming language, designed for the web. Processing.js makes your data visualizations, digital art, interactive animations, educational graphs, video games, etc. work using web standards and without any plug-ins.

JpGraph is an Object-Oriented Graph creating library for PHP >= 5.1 The library is completely written in PHP and ready to be used in any PHP scripts (both CGI/APXS/CLI versions of PHP are supported).

Protovis composes custom views of data with simple marks such as bars and dots. Unlike low-level graphics libraries that quickly become tedious for visualization, Protovis defines marks through dynamic properties that encode data, allowing inheritance, scales and layouts to simplify construction.