Slack's Block Kit Builder packaged as an Electron app.
Unfortunately, I haven't had the time to sign & distribute this app yet (see TODO section), so you'll need to clone and build the application yourself.
Clone the repo with git:
git clone https://github.com/amancevice/block-kitBuild and install the app on macOS with make:
make install- Persist Light/Dark theme on restart
- Sign & distribute app with Homebrew