Heurix.io - Heurix is a free heuristic evaluation tool that helps you work out how to improve your website.
D3.js - D3.js is a JavaScript library for manipulating documents based on data. D3 helps you bring data to life using HTML, SVG, and CSS.
UX Companion - A handy glossary of UX theories, tools and principles (iOS)
Chart.js - Easy, object oriented client side graphs for designers and developers.
Heurio - Do website reviews faster. Heurio eliminates the administration process and lets you focus on creating value in a collaborative and user-friendly way. Perfect for heuristic evaluation, design and development review, bug report, QA testing and more.
Google Charts - Interactive charts for browsers and mobile devices.