Connectivity Middleware — Head-to-Head

Kepware vs. Litmus

Both platforms connect legacy OT equipment to modern data pipelines. The difference is scope: Kepware is a focused, proven protocol translation engine with two decades of brownfield deployment history. Litmus collapses connectivity and edge compute into a single platform. The comparison is not about which has more protocol drivers. It is about whether you need a dedicated translation layer or a combined translation-and-compute architecture.

Criteria	Kepware (PTC)	Litmus
Platform
Primary function	Protocol translation and OPC server	Protocol translation and containerized edge compute
Platform scope	Connectivity only	Connectivity and edge application hosting
Deployment model	Windows server (KEPServerEX); Linux containers (Kepware Edge, in rollout)	Purpose-built edge hardware or VM; cloud management
Architecture	Centralized OPC server with driver channels	Distributed edge nodes with cloud orchestration
Protocol support
Driver count	150+ native drivers	250+ drivers
Legacy PLC depth	Industry-leading — DH+, DH-485, DF1, S5 AS511, decades of field-hardened driver history	Strong broad coverage; less field history on edge cases with oldest legacy hardware
OPC standards	OPC-DA, OPC-UA client and server	OPC-UA client; MQTT, Sparkplug B, REST
Modbus	Modbus RTU and TCP; full register mapping configuration	Modbus RTU and TCP; register mapping configurable
Edge capabilities
Edge compute	None — connectivity only	Containerized edge environment; deploy custom apps, ML inference, quality logic locally
Offline operation	Depends on host server availability	Full offline-first operation; buffers during WAN outages
Fleet management	Per-server; Kepware Edge adds remote config	Centralized fleet management across distributed nodes
Integration
MQTT / UNS	Via third-party MQTT client plug-in; Cirrus Link or equivalent required	Native MQTT and Sparkplug B publishing
Cloud connectors	Via MQTT plug-in or OPC-UA; separate configuration required	Native connectors to AWS, Azure, Databricks; Litmus Edge Bridge for Azure IoT Operations
Historian integration	Strong — direct OPC connections to AVEVA PI and major historians	Via MQTT or REST; less direct historian integration
Procurement
Licensing	Per-driver channel or suite; Windows server license	Per-node subscription; hardware or VM
Pricing	$$	$$
Watch	Kepware Edge Linux rollout ongoing — verify GA status and feature parity before committing	—

Protocol coverage sourced from vendor documentation. Verify driver availability for your specific device models and firmware versions before purchase.

Kepware wins when

Your environment includes legacy Allen-Bradley DH+ or DH-485, Siemens S5, or other older hardware where driver field history matters
Your architecture is built around OPC-DA or OPC-UA and you need a proven server
You are running Windows-based infrastructure and want the lowest-friction path
You need direct historian integration without additional middleware
Your connectivity requirements are well-defined and edge compute is handled separately

Litmus wins when

You need edge applications — ML inference, quality checks, local control logic — alongside data collection
You are building a MQTT/Sparkplug B UNS architecture and want native support without plug-ins
Your facilities have unreliable WAN and you need offline-first edge operation
You are managing connectivity across multiple distributed sites and need centralized fleet management
You want to consolidate connectivity middleware and edge compute into a single vendor relationship

The real decision

If your primary problem is connecting a complex brownfield environment — especially one with legacy Allen-Bradley or older Siemens hardware — to an existing OPC-based infrastructure, Kepware's driver depth and field history are hard to match. If you are building a new data architecture around MQTT, Sparkplug B, and cloud-native analytics, and you need edge compute alongside connectivity, Litmus collapses two procurement decisions into one.

The question that resolves it: do you already have an edge computing layer, or are you building one? If you have one, Kepware is the simpler connectivity choice. If you are building one, Litmus avoids a second vendor relationship.