MQTT brokers and UNS plumbing: 8 side-by-side comparisons

If you're building a Unified Namespace (UNS), the same shortlist keeps coming up: which MQTT broker, how to get Sparkplug B out of the edge, and whether you need a DataOps layer between the plant and IT. Here are the comparisons we maintain on PlantWired for exactly those choices. Each page lists the vendor, category, pricing model and the integrations we've documented, with sources.

The broker itself

• HiveMQ vs EMQX: both offer open-source and enterprise tiers. HiveMQ is frequently used as the backbone of a UNS; EMQX is positioned as a high-throughput broker.
• HiveMQ vs Eclipse Mosquitto: Mosquitto is the lightweight, free, open-source broker that often shows up first in a pilot.
• EMQX vs Eclipse Mosquitto: two open-source options at very different scales.
• Apache Kafka / Confluent vs HiveMQ: not the same job. MQTT moves device and plant data; Kafka is event streaming into enterprise data pipelines. Many stacks use both.

Sparkplug B at the edge

• HiveMQ vs Cirrus Link MQTT Modules: Cirrus Link's modules add MQTT/Sparkplug B to Ignition for report-by-exception data movement, and they commonly publish to a broker like HiveMQ, so this is more "how they fit" than "pick one".
• New to Sparkplug? Our explainer covers the topic namespace, Protobuf payloads and birth/death certificates: MQTT Sparkplug B explained.

Edge and DataOps

• Kepware vs Litmus Edge: a classic connectivity server versus an edge platform that collects, normalizes and forwards machine data.
• HighByte vs Litmus Edge: HighByte Intelligence Hub models and contextualizes OT data before it goes to cloud or IT systems.
• HighByte vs Flow Software: two takes on the information layer above the plant floor.

Putting it together

The full picture, layer by layer (connectivity, edge, broker, contextualization, storage, apps), is in The Unified Namespace (UNS) stack, explained with real tools. All 65 comparisons live at plantwired.vercel.app/compare.

Our data comes from public vendor sources and surely has gaps. If you run one of these in production and something's wrong or missing, tell us in the comments and we'll fix it.

PlantWired is a free, vendor-neutral map of factory software. A short weekly brief on new integrations is at plantwired.vercel.app.