For non-programmatic usage and verification, the extensions can be easier?
On a similar topic HIBP allowed people to request versioning via a custom HTTP Header, a Accept Content-Type, or a version segment in the URL path and approximately everyone went with option 3.
"For non-programmatic usage and verification," it should be served in a human-readable manner, typically including things like formatting, and maybe even syntax coloring if you're feeling nice.
Take my `Accept: text/html` and give me my HTML-ified JSON, dangit! ;)
I've actually seen APIs with "pretty=true" or "indent=4" type query parameters to emit formatted JSON for people before, though it doesn't go as far as HTML with syntax colouring.
On a similar topic HIBP allowed people to request versioning via a custom HTTP Header, a Accept Content-Type, or a version segment in the URL path and approximately everyone went with option 3.