WebGPU

WebGPU is the working name for a future web standard and JavaScript API for accelerated graphics and compute, aiming to provide "modern 3D graphics and computation capabilities". It is developed by the W3C "GPU for the Web" Community Group with engineers from Apple, Mozilla, Microsoft, Google, and others. 
Unlike WebGL, WebGPU is not a direct port of any existing native API. It is based on concepts in Vulkan, Metal, and Direct3D 12 and is intended to provide high performance on these modern graphics APIs across mobile and desktop platforms. 
The first conceptual prototype called NXT was showcased in early 2017 by Chromium team.
History.
On June 8, 2016, Google showed "Explicit web graphics API" presentation to the WebGL working group (during the bi-annual face to face meeting). The presentation explored the basic ideas and principles of building a new API to eventually replace WebGL, aka "WebGL Next".
On January 24, 2017, Khronos hosted an IP-free meeting dedicated to discussion of "WebGL Next" ideas, collided with WebGL working group meeting in Vancouver. Google team presented the NXT prototype implementing a new API that could run in Chromium with OpenGL, or standalone with OpenGL and Metal. NXT borrowed concepts from all of Vulkan, Direct3D 12, and Metal native APIs. Apple and Mozilla representatives also showed their prototypes built on Safari and Servo correspondingly, both of which closely replicated Metal API.
W3C Working Group.
On February 7, 2017, Apple's WebKit team proposed the creation of the W3C community group to design the API. At the same time they announced a technical proof of concept and proposal under the name
"WebGPU", based on concepts in Apple's Metal. The WebGPU name was later adopted by the community group as a working name for the future standard rather than just Apple's initial proposal. The initial proposal has been renamed to "WebMetal" to avoid further confusion.
The W3C "GPU for the Web" Community Group was launched on February 16, 2017. At this time, all of Apple, Google, and Mozilla had experiments in the area, but only Apple's proposal was officially submitted to the "gpuweb-proposals" repository.
Shortly after, on March 21, 2017, Mozilla submitted a proposal for WebGL Next within Khronos repository, based on the Vulkan design.
On June 1, 2018, citing "resolution on most-high level issues" in the cross-browser standardization effort, Google's Chrome team announced intent to implement the future WebGPU standard.
Technology.
WebGPU uses its own shading language called WGSL that is trivially translatable to SPIR-V. This choice is a compromise among three proposals: textual WebMetal by Apple, textual WebHLSL / WSL by Apple Safari, and binary SPIR-V by Mozilla.
Implementation.
Both Chrome and Firefox support WebGPU with SPIR-V, with work ongoing for the WGSL front-end. Safari supports WebGPU with WSL.