Cloudflare Workers derive their name from Web Workers, and more specifically Service Workers, the W3C standard API for scripts that run in the background in a web browser and intercept HTTP requests. Cloudflare Workers are written against the same standard API, but run on Cloudflare’s servers, not in a browser.

Source: Everyone can now run JavaScript on Cloudflare with Workers

It’s really nice that it uses the existing Service Worker API. I don’t have any use cases for this yet, but this will definitely be in the back of my mind. I wish there were a free tier to just play around with a handful of requests, but hopefully it’s similar enough to the Service Worker API that that won’t matter.