Puppeteer Go
I love Puppeteer - it lets me play around with the ideas of The Headless Web - that is running the web in a browser without a visible browser and even build tools like DOM-curl (Curl that runs JavaScript). Specifically I love scripting the browser to scrape, manipulate and interact with pages. One demo I wanted to make was inspired by Ire's Capturing 422 live images post where she ran a puppeteer script that would navigate to many pages and take a screenshot.