You can send in all GELF types via HTTP, including uncompressed GELF that is just a plain JSON string. https://docs.graylog.org/en/3.2/pages/sending_data.html#sending-in-log-data
With curl
curl -XPOST http://graylog.example.org:12202/gelf -p0 、
-d '{"short_message":"Hello there", "host":"example.org", "facility":"test", "_foo":"bar"}'With requests