The WHATWG works on a number of technologies that are fundamental parts of the web platform. They are organised somewhat arbitrarily based on the preferences of those editing the standard for those technologies.

Compatibility (@compatstandard)

The Compatibility Standard describes a collection of non-standard (and often vendor-prefixed) CSS properties and DOM APIs that web browsers need to support for compatibility with the de facto web.

Compression (@compressionapi)

The Compression Standard provides APIs for compressing and decompressing bytes using a set of the most common compression algorithms.

Console (@consolelog)

The Console Standard defines APIs for console debugging facilities.

DOM (@thedomstandard)

The DOM Standard defines the core infrastructure used to define the web.

Encoding (@encodings)

The Encoding Standard defines how character encodings work on the web.

Fetch (@fetchstandard)

The Fetch Standard defines the networking model for resource retrieval on the web.

File System (@whatfilesystem)

The File System Standard defines infrastructure and an API for file systems.

Fullscreen API (@fullscreenapi)

The Fullscreen API Standard defines how web pages can take over a user's entire screen (at the user's request), e.g., for gaming or to watch a video.

HTML (@htmlstandard)

The HTML Standard is a kitchen sink full of technologies for the web. It includes the core markup language for the web, HTML, as well as numerous APIs like Web Workers, localStorage, etc.

Infra (@infrastandard)

The Infra Standard aims to define the fundamental concepts upon which standards are built.

MIME Sniffing (@mimesniff)

The MIME Sniffing Standard defines algorithms used to determine the type of resources.

Notifications API (@notifyapi)

The Notifications API Standard provides an API to display notifications to alert users outside the context of a web page.

Quirks Mode (@quirksstandard)

The Quirks Mode Standard describes behaviours in CSS and Selectors that are not yet defined in the relevant specifications but that are nonetheless widely implemented.

Storage (@storagestandard)

The Storage Standard defines an API for persistent storage and quota estimates, as well as the platform storage architecture.

Streams (@streamsstandard)

The Streams Standard provides APIs for creating, composing, and consuming streams of data that map efficiently to low-level I/O primitives.

Test Utils (@testutils)

The Test Utils Standard defines internal APIs for automating testing of web platform features implemented in web browsers.

URL (@urlstandard)

The URL Standard defines the infrastructure around URLs on the web.

URL Pattern (@urlpatterns)

The URL Pattern Standard provides a web platform primitive for matching URLs based on a convenient pattern syntax.

Web IDL (@webidl)

The Web IDL Standard defines an interface definition language, Web IDL, that can be used to describe interfaces that are intended to be implemented in web browsers.

WebSockets (@whatsockets)

The WebSockets Standard provides APIs to enable web applications to maintain bidirectional communications with server-side processes.

XMLHttpRequest (@xhrstandard)

The XMLHttpRequest Standard defines the networking API exposed to scripts on the web.

The WHATWG also works on a number of ideas that aspire to become standards one day.