curl ... | json_pp
https://til.hashrocket.com/posts/pgyjvtuwba-pretty-print-json-responses-from-curl
curl --negotiate -u : <URL>
curl -H "Content-Type: application/json" -d '{"event": {"type": "member_left_channel", "user":"UQWGEV4UU", "channel": "test-meta"}}' -X POST http://localhost:8000/puzzles/slack_events/
curl -X POST https://example.com/endpoint
curl https://example.com/endpoint --data "foo=bar&baz=qux" -H "Custom Header: Foo"