Why does Gatsby start a second server at localhost:4000?

When I create a new gatsby app and run gatsby develop, it starts a server at localhost:8000 and then a second one on localhost:4000, where I’m able to query things like “allGatsbyPlugin”:

I can’t find documentation on gatsby starting things on ports other than localhost:8000. What is this, why is it here (I discovered it because it’s interfering with something else I run on port 4000), and can I change the port it runs on?

[KyleAMathews]

Yeah — 4000 wasn’t a good choice for the default recipes port as it’s used a lot for apps. Opened https://github.com/gatsbyjs/gatsby/pull/24665 to move it to 50400 which is a cool number as it’s a highly composite number! https://en.wikipedia.org/wiki/50,000

[bytheway875]

@KyleAMathews Thank you!