Comparison
OPC UA vs MQTT
Short answer: they solve different problems and increasingly work together. OPC UA is a secure, semantically rich standard for machine interoperability. MQTT is a lightweight publish-subscribe transport built for moving telemetry over unreliable links. You can even run OPC UA over MQTT.
| OPC UA | MQTT | |
|---|---|---|
| What it is | Full interoperability standard (model + services + transport) | A message transport (pub/sub) only |
| Data meaning | Rich, self-describing information model | None: payload is opaque (often JSON/Sparkplug) |
| Model | Client-server and PubSub | Publish-subscribe via a broker |
| Security | Built-in (certs, sign, encrypt, authz) | TLS + username/password; app must add more |
| Footprint | Heavier | Very lightweight |
| Scale (many nodes) | Good (esp. PubSub) | Excellent: millions of clients |
| Best at | Machine interoperability & control on the floor | Edge-to-cloud telemetry, poor networks |
When to choose OPC UA
- You need secure, bidirectional communication between machines and systems.
- You want vendor interoperability and self-describing data (browse a server and understand it).
- You're doing control or rich, on-demand access, not just telemetry.
When to choose MQTT
- You're pushing data edge-to-cloud, especially over limited or unreliable links.
- You need to connect thousands to millions of lightweight devices.
- You want a minimal footprint and a simple broker-based fan-out.
They combine. OPC UA PubSub can use MQTT as its transport: you get OPC UA's rich, standardised payload and MQTT's lightweight, scalable delivery. This is a common Industry 4.0 pattern for getting modelled shop-floor data into the cloud.
A simple decision guide
| If your priority is… | Reach for… |
|---|---|
| Interoperability between machine vendors | OPC UA |
| Control & write-back to equipment | OPC UA |
| Massive edge-to-cloud telemetry | MQTT |
| Modelled data and cloud scale | OPC UA PubSub over MQTT |
Once the data is flowing (over OPC UA, MQTT, or both) Jemba turns it into ranked, costed actions for the floor.
See Jemba →FAQ
Is MQTT part of OPC UA?
MQTT is independent, but OPC UA's PubSub can use MQTT as a transport, so the two are frequently deployed together.
What is Sparkplug?
Sparkplug is a specification that adds structure, state and payload definition on top of plain MQTT. It overlaps with some of what OPC UA's information model provides.
Which is more secure?
OPC UA has richer security built into the standard (certificates, security modes, authorisation). MQTT relies on TLS plus whatever the application layer adds.
Last updated 4 September 2026 · Educational resource.