How to Choose Bow Tie Software
Most bow tie software will draw you a competent diagram. The differences that actually bite show up two years in — in what it costs to keep the diagram true, what you can prove about its history, and what you still own if you leave.
The shape of the market
Bow tie analysis has been standard practice in high-hazard industry for decades, and the established tools reflect where they came from: a Windows desktop application for building diagrams, a separately licensed server product once an organisation needs one governed repository across sites, and further modules bolted alongside for incidents, audits and reliability work. Capable software, but the shape has consequences — several licences, a server estate to run, and a diagram that tends to be refreshed for a formal issue rather than kept current between them.
SAFOPS was built for the second problem. It covers the bow tie diagram, the safety case around it, and the golden thread between them in one continuous workflow — from initiating event through barrier substantiation to ALARP justification — with no add-on modules and no server to stand up.
The dimensions that matter
Where the two approaches genuinely diverge, on the points safety teams raise most often during procurement.
| Dimension | SAFOPS | Conventional bow tie suites |
|---|---|---|
| Where the data lives | A single structured Excel .xlsx workbook per project. You can open it, back it up, put it on an encrypted drive or commit it to version control without any special software. |
Typically a proprietary project file on a desktop client, with a separately licensed server product where a central repository is needed. |
| Multi-site rollup | In the base product. Shared barriers are resolved once rather than double-counted across cases, and each case keeps its own methodology. | Commonly the server tier — a second product and a second licence. |
| Quantified risk, not just colour | Barrier credit is computed rather than asserted. Each project’s Safety Class Tiers carry a PFD/PFH reliability ladder — Class 1–3 PFD/PFH for ONR SAPs, SIL 1–4 on PFH for EN 50126 rail, SIL 1–3 SIF for ISO 17776 — and every consequence carries a deterministic residual-frequency estimate: the exposure group’s summed initiating-event frequency multiplied through the PFD of every barrier actually scoped to protect it. A real number sits next to the qualitative category. | Varies widely. Many tools are qualitative at the diagram level, with quantification depending on which modules are licensed. Establish early whether the PFD/PFH treatment your standard requires is included or extra. |
| Change provenance | Every edit is chained into a SHA-256 hash chain, so the history is tamper-evident rather than simply recorded. A file cannot drift silently. | A revision history is near-universal. Whether it is tamper-evident — provable, not just present — is a separate question worth asking explicitly. |
| Air-gapped operation | Supported, including the optional AI copilot, which can run on a local model on your own hardware so nothing leaves your network. | Desktop clients often suit restricted networks well. Server tiers and any cloud-hosted AI features may not — check both halves. |
| Scope of the base product | Bow tie diagrams, safety case, golden thread, change impact analysis, risk matrices and automated reporting in one continuous workflow, with no add-on modules and no second licence. | Adjacent disciplines — incidents, audit, reliability — are commonly separate modules, priced separately. |
| Cost of staying current | Change impact analysis is deterministic: remove a barrier and the tool tells you which fault sequences and which consequences just moved. | Often manual. The diagram is accurate on the day it is issued, and drifts from the plant until someone rebuilds it. |
See a real bow tie diagram, not a brochure
The fastest way to judge any of this is to use one. The link below opens a real SAFOPS bow tie diagram in your browser — click the barriers, follow a fault sequence from initiating event to consequence, and see the deficiencies sitting on the plates. No sign-up, no sales call.
Bring your existing bow ties with you
Already have bow ties, hazard logs or a barrier register in a spreadsheet? Start from what you have rather than from a blank page.