Unreachable questions
Find supported rules that can never work with the answer values supplied by the definition.
Evidence-backed checks for conditional forms
Find form-logic bugs
before they become missing data.
FormPath checks SurveyJS JSON, REDCap data dictionaries, and FHIR Questionnaires for questions that can never appear and references to fields that no longer exist. For supported SurveyJS forms, it also finds hidden answers that still control later questions. It shows the exact rule, a working answer example or proof where possible, and anything it could not safely check. Everything runs in your browser.
Your form definition is not uploaded. No participant data is needed.
Controlling rule
({loan-purpose} = 'house-purchase') and ('property-use' == 'residental')Definition actually offers
{property-use}: 'residential', 'buy-to-let', 'holiday-let'Proven unreachable
The rule compares the text “property-use” instead of the form answer, then misspells “residential.” No available response can make the mortgage-status question appear.
PROVENFINITE DOMAIN
64Public artifacts across SurveyJS, REDCap, and FHIR Questionnaire in a retained July 2026 review
7Files with a published supported defect in native SurveyJS or a translated model
4Distinct defect shapes in this convenience review—not a prevalence estimate
0Form definitions sent to our server
What it catches
Logic can fail silently. The missing data arrives later.
A form still opens when an answer code changes, a reference goes stale, or a conditional question becomes impossible to reach. FormPath turns that silent behavior into reviewable evidence.
Proof when possible
Broken references
Surface renamed, missing, and malformed dependencies before they blank out downstream fields.
Stale-answer hazards
Find when a hidden answer can still affect a later question. On supported SurveyJS forms, FormPath may also reproduce the sequence: answer the question, hide it, and confirm that its old value still controls later logic.
Revision impact
Separate confirmed regressions from intentional behavior changes and changes in analysis coverage.
Why this is different
A preview shows the path you clicked. FormPath checks what you might never find.
Schema validation can tell you whether a file is well formed. FormPath asks whether supported conditional rules can actually be satisfied—and records the boundary when it cannot answer safely.
- 1
A working answer example
When a question can appear, see an answer combination that makes it visible. SurveyJS examples are checked in SurveyJS itself.
- 2
Proofs, not vague warnings
When a supported rule is impossible, see the conflicting conditions and the software versions used to check them.
- 3
Honest unknowns
Remote choices, custom functions, dynamic rows, and application-controlled behavior are listed plainly instead of being counted as a pass.
A practical workflow
From source file to evidence you can keep.
- 1
Bring the definition
Paste or drop SurveyJS JSON, a REDCap data dictionary, or a FHIR Questionnaire. Use definitions only—never participant responses.
- 2
Run the analysis
FormPath tests the answer values in the definition, finds combinations that make questions appear, proves supported impossible rules, and—where eligible—tries the SurveyJS answer sequence behind a hidden-value bug.
- 3
Keep the regression suite
Download a compact set of answer combinations that preserves the question visibility and rule outcomes FormPath observed. These are reusable test inputs, not complete respondent journeys.
Troubleshooting by ecosystem
One starting point for each supported definition.
Start with a concrete SurveyJS, REDCap, or FHIR Questionnaire symptom. Each guide traces the definition-level rule and keeps native-runtime evidence separate from translated conclusions.
SurveyJS question not showing
Diagnose a SurveyJS question that never appears by checking its stored values, visibleIf rule, parent visibility, and behavior controlled by the surrounding app.
Diagnose this failureREDCap branching logic not working
Trace a REDCap branch that never appears by checking field names, stored choice codes, checkbox syntax, and logic that depends on the running project.
Diagnose this failureFHIR enableWhen answer-code mismatch
Check whether a FHIR Questionnaire enableWhen condition expects a code that its source item never offers, while preserving terminology and runtime limits.
Diagnose this failureSupported definitions
SurveyJS results are cross-checked. REDCap and FHIR translations are always labeled.
Working SurveyJS answer combinations are replayed in SurveyJS. Impossible supported rules use a finite proof whose encoding is sample-checked against SurveyJS for that form; supported generated rule shapes are exhaustively cross-checked in release tests. REDCap and FHIR rules are translated and labeled. Anything FormPath cannot check stays visible.
01SurveyJS replay + rule proofs
SurveyJS
Survey JSONWorking answer combinations are replayed in SurveyJS. Supported impossible rules are proved from the form's listed values after the rule encoding is sample-checked against SurveyJS for that form. Supported generated rule shapes are exhaustively cross-checked in release tests.
SurveyJS troubleshooting guides02Translated-model evidence
REDCap
Data dictionary CSVSupported branching rules are converted to a tested internal format. FormPath does not run inside REDCap.
REDCap scope and examples03Translated-model evidence
FHIR
Questionnaire JSONSupported enableWhen rules are converted to a tested internal format. FormPath does not run inside a FHIR application.
FHIR Questionnaire scopeNo signup · no upload
Check the next revision before it reaches respondents.
Start with a synthetic sample or bring a definition. Export the full report as JSON or readable Markdown; the analysis stays in this browser unless you choose to download it.
Open the analyzer