online collection

A gallery of (combinatorial) graphs produced by using LaTeX and TikZ, along with their source code.

These pages present interactive graphical polyhedra organized in several categories. Each polyhedron's page contains a 3-dimensional virtual model of the polyhedron, followed by a summary of the polyhedron's vital statistics. The model provides an opaque visual mode, a translucent visual mode, and a metrics mode. In the visual modes, the polyhedron can be rotated and scaled, the perspective can be changed, and individual faces can be examined in isolation. The metrics mode computes the polyhedron's vital statistics empirically.

A repository of the Max Planck Institute for Mathematics in the Sciences in Leipzig, dedicated to mathematical research data, namely all digital objects that arise during the process of doing research or are a result thereof. It is open to contributions with some restrictions: publications are only possible for scientists of the MPI MiS and their collaborators.

Contains a gallery of mathematical artwork as well as a list of mathematical art exhibitions. These include fashion, art, and film (as of now).

Interactive online gallery with 3 Bruhat-Tits buildings represented in 3D. The 3D picture can be rotated and displayed at different scales. 
The drawing process is detailed in the following arXiv.org PDF file: https://arxiv.org/pdf/2011.11707v2

A collection of chart types classified by types of input data format. For each chart type, the website includes the definition, common caveats, and links to guides on using the charts in Python, d3js, React, and R.

A library of different types of information visualizations. Searchable by function and type of visualization. Also contains a list of data visualization resources, including data sources, blogs, learning resources, and tools. Not open to contributions, but you can request to include your work in the Examples section for £3.50 per link per year.

A curated collection of links to resources for data visualization, including textbooks, lecture notes, tutorials, and other learning material. Not open to contributions.

Contains examples of pictures made with TikZ. Each illustration comes with a short description and its source code. Everything is licensed under CC-BY-SA and can therefore be reused.

A collection of interactive illustrations of complex systems and complex dynamical processes. All illustrations include explanations of the underlying systems and of the illustration, sometimes including references. Code for selected illustrations is available in a GitHub repository. The website states they are open to corrections and ideas by email, but no other way to contribute.