There doesn't seem to be a UI function for this, so if you're stuck up a creek like I am.
curl -s \
-H "Authorization: Basic $(echo -n 'username:password' | base64)" \
http://graylog-server:9000/api/streams \
| jq '
.streams[] |
select(.outputs | length > 0) |
{
id: .id,
title: .title,
outputs: [(
.outputs[] | {id: .id, title: .title}
)]
}'
You'll end up with a minimal JSON doc with the names and IDs of all the streams, and all the outputs mapped to them.