Infusion, originally an initiative of the Fluid community since 2008, is a JavaScript library enabling the creation of flexible software. Versions 1 through 4 of Infusion, documented and hosted on the Fluid project’s site, were relatively conventionally structured libraries supporting the development of various UI widgets.
Since 2024 a comprehensive rewrite of Infusion has been underway for version 6 based on reactive primitives throughout, structuring it as a software substrate constituting an integration domain.