NPAPI meaning in Softwares ?

Netscape Plugin Application Programming Interface (NPAPI) is an application programming interface (API) of the Web Browsers that allows plugins to be integrated.

Initially developed for Netscape browsers, starting in 1995 with Netscape Navigator 2.0, it was subsequently adopted by other browsers.

In NPAPI architecture, a plugin declares content types (e.g. "audio/mp3") that it can handle. When the browser encounters a content type it cannot handle natively, it loads the appropriate plugin, sets aside space within the browser context for the plugin to render and then streams data to it. The plugin is responsible for rendering the data. The plugin runs in-place within the page, as opposed to older browsers that had to launch an external application to handle unknown content types. NPAPI requires each plugin to implement and expose approximately 15 functions for initializing, creating, deleting and positioning plugin content. NPAPI also supports scripting, printing, full-screen plugins, windowless plugins and content streaming.

NPAPI was frequently used for plugins which required intensive, low-level performance such as video players, including Adobe Flash Player and Microsoft Silverlight, as well as platforms for web applications such as the Java Runtime Environment.

NPAPI support among major started to wane since 2015 and it was gradually deprecated over the last years. With the advent of HTML5, all major web browsers have removed support for 3rd party NPAPI plugins for security reasons. There are some smaller browsers such as Pale Moon and Waterfox Classic that still support NPAPI plugins.