ECharts

ECharts renders everything from simple bar charts to complex 3D globes, geomaps, and real-time streaming dashboards, all client-side with no server dependencies. It handles everything from a simple dashboard widget to a full geographic heatmap with 100K data points.

Apache Foundation project, TypeScript core. The feature set is massive: 20+ chart types, animations, responsive layouts, dataset transforms, and a visual builder at echarts.apache.org that lets you configure charts before writing code. It handles real-time streaming data and lazy-loads chart types you don't use.

Everything is free. No paid tier, no hosted version, no premium charts behind a paywall. Apache 2.0 license means you can use it in commercial products without restrictions. Solo developers get a production-grade charting library for $0. Teams of any size get the same thing. The community is enormous. StackOverflow answers for almost any question.

The catch: the API surface is huge. Configuration objects get deeply nested and the docs, while comprehensive, assume you already know what you want. If you need something quick and simple, Chart.js gets you there faster. If you need advanced interactivity or large datasets, ECharts is the better pick.