If you are working on Mac or Linux you can easily download WebKit or Safari Technical Preview from this link https://webkit.org/downloads/
But after the latest changes in webkit build pipeline, this can be done in easier way:
Introducing WebKit Build Archives
WebKit contributors have long relied on the WebKit Nightly builds. The WebKit project has been posting these builds…
Because build artifacts stored for 14 days, they can be downloaded from storage. There is a steps how it can be done by self.
There is list of Webkit Windows builds:
There link to log where builds are stored:
So we can use this link to download build, be prepared it quite big more that 200 Mb.
There can be found
jsc.exe that allow to test latest WebKit features. Also be aware that to run
jsc.exe Apple Application support(AAS) libs should be installed, I’ve installed
iTunes for that, and possible
cygwin as well. I’ve checked on my dev machine and this components were already installed.