PhosphorJS provides a rich set of widgets, layouts, events, and data structures. These enable developers to construct advanced, production-quality, desktop-like web applications that would be otherwise impossible using CSS alone.


PhosphorJS libraries cover a range of topics including message passing, signaling, attached properties, data structures, widgets, and layouts.

Each is separately installable via NPM, allowing developers to use them individually, according to their needs.


Speed matters.

To maintain a 60fps refresh rate in response to user interaction, an application has ~16ms to perform all logic calculations, DOM manipulations, reflows, and repaints. Meeting this threshold is challenging for sizable, multi-tab, single-page, applications.

PhosphorJS widgets and layouts are written with efficiency in mind, minimizing reflows whenever possible and consistently achieving sub-millisecond layout times.

This leaves as much of the time-slice as possible to be used for the execution of business logic.


PhosphorJS plays well with existing web frameworks and libraries. It is not an opinionated and rigid toolset that constrains the developer to a specific model or data flow.

Rather, it allows the developer to build high-performance user interfaces with well-structured widget hierarchies in a flexible manner.