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Manufacturing · head to head

Flow Software vs Kepware Server

Flow Software logo

Flow Software

Manufacturing

Manufacturing KPI and OEE calculation engine with published list prices, licensed by measure count

From
$11390/one-time
Rated
-
Full reviewWebsite
Kepware Server logo

Kepware Server

Manufacturing

Industrial connectivity server translating 150-plus PLC protocols into OPC UA, formerly KEPServerEX

From
On request
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Flow Software the 11,390 dollar Starter licence caps at 250 measures and events, which a multi-line plant exhausts quickly once each line contributes a dozen calculations, forcing a jump to the 62,230 dollar tier.; Kepware Server the base server is the small part of the bill; driver suites are priced by protocol family, and a mixed-vendor plant buys several, which is how a connectivity layer alone reaches tens of thousands of dollars.
  • They diverge on capability: Flow Software covers Calculation engine, Kepware Server covers 150-plus device drivers.
  • Prices and features above were last checked on 1 September 2026.

Where they differ

Only the attributes on which Flow Software and Kepware Server actually diverge.

Attributes where Flow Software and Kepware Server differ
AttributeFlow SoftwareKepware Server
Starting price$11390/one-timeOn request
Pricing modelOne-time purchasequote
PlatformsWindows, WebWindows, Linux

Identical on both: free tier (No), user rating (Not yet rated), category (Manufacturing).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Flow Software

  • Calculation engine
  • Measure model
  • Historian connectors
  • Manual data entry
  • Event framing
  • Excel and Power BI output
  • Flow dashboards
  • AI Gateway

Only in Kepware Server

  • 150-plus device drivers
  • OPC UA server
  • IoT Gateway
  • DataLogger
  • Redundancy Master
  • Security Policies
  • Configuration API
  • Kepware Edge

What people use each for

The jobs each tool is most often brought in to do.

Flow Software

  • A brewery replacing a fragile network of OEE spreadsheets with governed calculations from the same historian datanot Kepware Server
  • Reporting specific energy consumption per tonne against an ISO 50001 audit where the calculation method must be documentednot Kepware Server
  • Feeding Power BI plant dashboards from a historian without giving analysts direct tag-level accessnot Kepware Server
  • A site that needs lab results typed in and combined with automated tag data in the same yield calculationnot Kepware Server

Kepware Server

  • Feeding a historian from a mixed plant of Allen-Bradley and Siemens PLCs without writing per-protocol driversnot Flow Software
  • Publishing CNC machine state from FANUC and Haas controls to an OEE system over MQTTnot Flow Software
  • Bridging legacy serial Modbus devices into an OPC UA architecture during a phased controller replacementnot Flow Software
  • Running redundant collection servers so a cloud analytics pipeline does not lose data during Windows patchingnot Flow Software

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Flow Software

  • The 11,390 dollar Starter licence caps at 250 measures and events, which a multi-line plant exhausts quickly once each line contributes a dozen calculations, forcing a jump to the 62,230 dollar tier.
  • The Unlimited licence requires every engine on a single server or VM, so any multi-server or multi-site topology goes straight to Distributed at roughly double the price with no intermediate option.
  • Maintenance renews at about fifteen percent of the installed base annually, so a large perpetual estate carries a five-figure recurring cost that the headline perpetual price hides.
  • It is a Windows product with a Microsoft data stack, so Linux or container-native deployment strategies do not apply and the server has to be managed on the plant Windows estate.
  • It calculates and reports but does not collect from equipment itself, so an existing historian or OPC layer is a prerequisite and Flow adds cost on top of that rather than replacing it.

Kepware Server

  • The base server is the small part of the bill; driver suites are priced by protocol family, and a mixed-vendor plant buys several, which is how a connectivity layer alone reaches tens of thousands of dollars.
  • KEPServerEX to Kepware Server 7 is a migration rather than an in-place upgrade, and driver entitlements do not always transfer cleanly, so budget for revalidating every channel.
  • The full driver portfolio is Windows-only; the Linux product, Kepware Edge, supports a subset of drivers and is subscription-licensed by tag count, so an edge-first architecture cannot simply reuse the Windows configuration.
  • Three names have been in circulation for the same lineage, and quotes, forum answers and integrator experience still mix KEPServerEX, ThingWorx Kepware Server and Kepware Server, which produces mismatched proposals.
  • It is a translation layer with no storage, contextualisation or visualisation of its own, so it is always an addition to a historian or platform purchase rather than a substitute for one.

Pricing, plan by plan

Flow Software

$11390/one-time
  • Starter$11390/one-time
    • 250 KPI measures and events
    • Single server deployment
    • First year of software maintenance included
  • Unlimited$62230/one-time
    • Unlimited KPI measures and events
    • All engines must run on one server or dedicated VM
    • First year of maintenance included
  • Distributed$128450/one-time
    • Unlimited measures with engines distributed across multiple servers
    • Required for multi-server and multi-site deployments
    • Available as an annual subscription at 34,250 USD instead

Kepware Server

On request
  • Kepware Server$undefined/year
    • Base server as a perpetual licence with annual maintenance, or subscription
    • Driver suites priced by protocol family and bought separately from the server
    • Advanced plug-ins such as IoT Gateway, DataLogger and Redundancy Master licensed individually

Which should you pick?

Choose Flow Software if

  • You need calculation engine.
  • You work on Windows, Web.
  • You also want measure model.
Flow Software review

Choose Kepware Server if

  • You need 150-plus device drivers.
  • You work on Windows, Linux.
  • You also want opc ua server.
Kepware Server review

Questions people ask

Is Flow Software or Kepware Server better?
Neither clearly leads. Flow Software starts at $11390/one-time and Kepware Server at On request, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Flow Software or Kepware Server?
Flow Software starts at $11390/one-time and Kepware Server at On request.
Does Flow Software or Kepware Server run on more platforms?
Flow Software runs on Windows, Web. Kepware Server runs on Windows, Linux.
What is Flow Software best used for?
Flow Software is most often used for a brewery replacing a fragile network of oee spreadsheets with governed calculations from the same historian data, reporting specific energy consumption per tonne against an iso 50001 audit where the calculation method must be documented, feeding power bi plant dashboards from a historian without giving analysts direct tag-level access, a site that needs lab results typed in and combined with automated tag data in the same yield calculation. Of those, a brewery replacing a fragile network of oee spreadsheets with governed calculations from the same historian data and reporting specific energy consumption per tonne against an iso 50001 audit where the calculation method must be documented are not what Kepware Server is typically brought in for.
What can Flow Software do that Kepware Server cannot?
Flow Software covers Calculation engine, Measure model, Historian connectors, Manual data entry. Kepware Server covers 150-plus device drivers, OPC UA server, IoT Gateway, DataLogger.

Answered from the vendors’ own pages

Flow Software: Does Flow publish real prices?

Yes. Starter is 11,390 USD perpetual for 250 measures, Unlimited is 62,230 USD perpetual or 16,595 USD a year, and Distributed is 128,450 USD perpetual or 34,250 USD a year.

Kepware Server: Is KEPServerEX discontinued?

The name is. KEPServerEX and ThingWorx Kepware Server have been unified into Kepware Server, currently version 7, and the older names are being retired.

Flow Software: Is perpetual licensing still offered?

Yes, at every tier, with the first year of maintenance included and renewal at roughly fifteen percent per year. Subscription is available on Unlimited and Distributed only.

Kepware Server: Is a perpetual licence still available?

Yes for the Windows server, with annual maintenance. Kepware Edge on Linux is subscription-only.

Flow Software: Do I need a historian as well?

Effectively yes. Flow reads from historians, databases and OPC sources; it is a calculation layer, not a data collector.

Kepware Server: What drives the price?

The number and type of driver suites, not the number of tags on the Windows product. Kepware Edge is priced by tag count.

Flow Software: What counts as a measure?

Each configured KPI or event definition. A single line typically consumes ten to thirty, which is what makes the 250 Starter cap tighter than it looks.

Kepware Server: Can I evaluate it before buying?

Yes. The runtime works for two hours at a time without a licence, indefinitely, which is enough to prove connectivity but not to run production.

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