From the article:

Over the last few weeks, three new products have announced themselves on Hacker News to great success, each making the frontpage:

• Sprites (fly.io) with 508 votes and hit #7

• exe.dev with 457 votes and hit #2

• shellbox.dev with 316 votes and hit #4

All three have a very simple pitch: they will give you full access to Linux virtual machines to act as a sandboxed developer environment in the cloud.