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Manufacturing · head to head

OpenBOM vs Siemens WinCC Unified

OpenBOM logo

OpenBOM

Manufacturing

Cloud bill of materials and part catalogue management priced per seat, with free read-only users

From
Free
Rated
-
Full reviewWebsite
Siemens WinCC Unified logo

Siemens WinCC Unified

Manufacturing

Siemens web-based HMI and SCADA platform, licensed by PowerTag count inside TIA Portal

From
On request
Rated
-
Full reviewWebsite

The short version

  • Only OpenBOM has a free tier, so it costs nothing to try first.
  • Each has a real cost: OpenBOM pricing has three axes, editing seats plus data record count plus per-seat CAD add-ins at $25 to $45 each, so the real annual cost is well above the advertised per-seat figure.; Siemens WinCC Unified licensing counts PowerTags, and archived tags are licensed separately from displayed tags, so a project that adds historian logging late can breach a tier and trigger an unbudgeted step-up purchase.
  • They diverge on capability: OpenBOM covers Multi-level BOMs, Siemens WinCC Unified covers TIA Portal engineering.
  • Prices and features above were last checked on 1 September 2026.

Where they differ

Only the attributes on which OpenBOM and Siemens WinCC Unified actually diverge.

Attributes where OpenBOM and Siemens WinCC Unified differ
AttributeOpenBOMSiemens WinCC Unified
Starting priceFreeOn request
Pricing modelPer user per monthquote
Free tierYesNo
PlatformsWeb, Windows, macOS, APIWindows, Web, Linux

Identical on both: 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 OpenBOM

  • Multi-level BOMs
  • Part catalogue
  • CAD add-ins
  • Change management
  • Free read-only users
  • REST API

Only in Siemens WinCC Unified

  • TIA Portal engineering
  • HTML5 runtime
  • PowerTag licensing tiers
  • Unified Comfort Panels
  • Parameter Control
  • Performance Insight
  • JavaScript scripting
  • OPC UA server and client

What people use each for

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

OpenBOM

  • A hardware startup replacing a shared BOM spreadsheet before its first contract manufacturing runnot Siemens WinCC Unified
  • A contract manufacturer sharing structured BOMs with customers who should see but not edit themnot Siemens WinCC Unified
  • An electronics team pulling BOMs straight out of Altium and mechanical CAD instead of retyping themnot Siemens WinCC Unified
  • A small manufacturer that needs part numbering and revision discipline but cannot fund a PLM projectnot Siemens WinCC Unified

Siemens WinCC Unified

  • A machine builder standardising on S7-1500 who wants HMI screens engineered in the same project as the PLC codenot OpenBOM
  • Replacing a WinCC V7 plant SCADA before the 2027 support cut-off without changing controller vendornot OpenBOM
  • A line supervisory system where operators and supervisors need browser access from tablets with no client software rolloutnot OpenBOM
  • A plant already committed to the TIA Portal toolchain, where the cost of a rival SCADA is the second engineering environment and the second set of skills rather than the licencenot OpenBOM

Where each one falls short

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

OpenBOM

  • Pricing has three axes, editing seats plus data record count plus per-seat CAD add-ins at $25 to $45 each, so the real annual cost is well above the advertised per-seat figure.
  • Paying yearly nearly halves the seat price, from $55 to $30 and $165 to $90, so monthly billing carries an unusually heavy penalty for teams that want flexibility.
  • Change management, revision control and CAD file management are absent from the entry Team plan, so the cheapest tier is a catalogue rather than a working PLM.
  • It lacks the approval workflows, effectivity dating and audit depth that regulated medical and aerospace suppliers need, so companies pursuing ISO 13485 or AS9100 typically migrate away.
  • Record count is metered separately and a large imported part library can push a small team into a higher data tier without adding a single user.

Siemens WinCC Unified

  • Licensing counts PowerTags, and archived tags are licensed separately from displayed tags, so a project that adds historian logging late can breach a tier and trigger an unbudgeted step-up purchase.
  • There is no migration tool that converts a WinCC V7 project to Unified, so leaving the classic line before its 2027 support end means rebuilding screens, scripts and alarm configuration by hand.
  • Scripting moved from VBScript to JavaScript, which invalidates the script libraries in-house engineers accumulated over a decade on classic WinCC.
  • It is effectively bound to the Siemens controller stack; connecting Rockwell or Mitsubishi PLCs works through OPC UA but loses the shared tag database that is the main reason to buy it.
  • Three unrelated products share the WinCC name, and buyers who specify WinCC without saying Unified, V7 or OA regularly receive quotes for the wrong platform with different licensing and a different contractor pool.

Pricing, plan by plan

OpenBOM

Free
  • FreeFree
    • Up to 2,000 data records
    • Basic BOM and catalogue management
    • Non-commercial and educational use
  • Professional Team$55/month
    • $30 per seat per month billed yearly
    • BOM management, part catalogue, inventory
    • RFQ and purchase orders
  • Company$165/month
    • $90 per seat per month billed yearly
    • Everything in Team
    • CAD file management and revision control
  • Enterprise$undefined/year
    • Single sign-on
    • Custom integrations
    • Private or custom hosting

Siemens WinCC Unified

On request
  • WinCC Unified$undefined/year
    • Engineering licence per seat within TIA Portal
    • Runtime licensed in PowerTag tiers, from 100 tags to unlimited
    • Archived tags licensed separately from displayed process tags

Which should you pick?

Choose OpenBOM if

  • You need multi-level boms.
  • You want to start without paying.
  • You work on Web, Windows, macOS, API.
  • You also want part catalogue.
OpenBOM review

Choose Siemens WinCC Unified if

  • You need tia portal engineering.
  • You work on Windows, Web, Linux.
  • You also want html5 runtime.
Siemens WinCC Unified review

Questions people ask

Is OpenBOM or Siemens WinCC Unified better?
Neither clearly leads. OpenBOM starts at Free and Siemens WinCC Unified at On request, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, OpenBOM or Siemens WinCC Unified?
OpenBOM has a free tier; the other does not. Paid plans start at Free for OpenBOM and On request for Siemens WinCC Unified.
Does OpenBOM or Siemens WinCC Unified run on more platforms?
OpenBOM runs on Web, Windows, macOS, API. Siemens WinCC Unified runs on Windows, Web, Linux.
Can I use OpenBOM for free?
Yes. OpenBOM has a free tier, so you can try it without paying. Siemens WinCC Unified starts at On request.
What is OpenBOM best used for?
OpenBOM is most often used for a hardware startup replacing a shared bom spreadsheet before its first contract manufacturing run, a contract manufacturer sharing structured boms with customers who should see but not edit them, an electronics team pulling boms straight out of altium and mechanical cad instead of retyping them, a small manufacturer that needs part numbering and revision discipline but cannot fund a plm project. Of those, a hardware startup replacing a shared bom spreadsheet before its first contract manufacturing run and a contract manufacturer sharing structured boms with customers who should see but not edit them are not what Siemens WinCC Unified is typically brought in for.
What can OpenBOM do that Siemens WinCC Unified cannot?
OpenBOM covers Multi-level BOMs, Part catalogue, CAD add-ins, Change management. Siemens WinCC Unified covers TIA Portal engineering, HTML5 runtime, PowerTag licensing tiers, Unified Comfort Panels.

Answered from the vendors’ own pages

OpenBOM: Is OpenBOM free?

There is a genuine free tier limited to 2,000 data records and aimed at non-commercial and educational use. Commercial teams start at $30 per seat per month billed yearly.

Siemens WinCC Unified: Should I buy WinCC Unified or WinCC V7?

Unified, for any new project. V7 and V8 receive no new features and support ends in 2027.

OpenBOM: Do I pay for people who only look at BOMs?

No. Read-only users are unlimited and free on every paid plan, which is the main reason the total cost undercuts seat-for-seat PLM tools.

Siemens WinCC Unified: Is WinCC OA the same product?

No. WinCC OA came from ETM, has its own engineering environment and licensing, and is aimed at very large distributed systems. It shares only the brand.

OpenBOM: Are the CAD add-ins included?

No. They are $25 per seat per month billed yearly, $45 monthly, and require an active Team or Company subscription.

Siemens WinCC Unified: What is a PowerTag?

An externally connected process variable in the runtime. Internal tags do not count, but archived tags are licensed separately from displayed ones.

OpenBOM: Can OpenBOM replace a full PLM?

For a startup, usually yes. For regulated manufacturing needing controlled workflows and full audit trails, no.

Siemens WinCC Unified: Can operators use it from a browser without installing anything?

Yes, the runtime is HTML5, but concurrent browser clients need WebUX or Unified client licences.

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