DevExtreme

If you need production-grade UI components for data-heavy web apps (grids, charts, schedulers, pivot tables), DevExtreme gives you 70+ widgets that handle the complex stuff most component libraries don't touch. Think enterprise dashboards, admin panels, and anything with serious data tables. It works with React, Angular, Vue, and jQuery.

The source code is on GitHub, but this is not a typical open source project. DevExpress, the company behind it, sells commercial licenses. The GitHub repo is "source-available" for transparency and issue tracking, not for free commercial use. You can evaluate it freely, but production use requires a paid license.

Pricing starts around $1,099/year for a single developer license (DevExtreme Complete). That gets you the full component set, priority support, and updates. Enterprise and Universal bundles that include server-side controls go higher. For teams, the per-seat cost adds up fast.

The catch: this is a commercial product with an open GitHub repo, not an open source project you can self-host for free. The license explicitly prohibits redistribution. If you need free, look at AG Grid (community edition), Ant Design, or Material UI. DevExtreme's strength is in the data grid and scheduler components, which are genuinely best-in-class for complex use cases, but you're paying for that quality.