Free FHIR Validator for JSON Resources
Client-side validation of FHIR JSON resources. Identifies structure and syntax errors quickly.
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Validate FHIR JSON Before It Reaches Production
FHIR validation helps developers and integration teams catch structural issues before a resource is sent to an API, stored in a data lake, or mapped into a downstream clinical workflow. A malformed Patient, Observation, Encounter, Condition, MedicationRequest, or Bundle can cause rejected API calls and hard-to-debug data quality problems.
This free FHIR validator is designed for quick inspection during development, QA, interface troubleshooting, HL7 to FHIR mapping, and C-CDA to FHIR conversion planning. Browser-side processing helps reduce exposure because validation can happen locally in the browser.
Supported FHIR Resource Types
| Resource | Common purpose | Fields often reviewed |
|---|---|---|
| Patient | Demographics and identity | name, birthDate, gender, identifier |
| Observation | Vitals, lab results, survey answers | code, status, value[x], effectiveDateTime |
| Encounter | Visit and care setting context | status, class, subject, period |
| Condition | Problems and diagnoses | code, subject, clinicalStatus, onsetDateTime |
| MedicationRequest | Medication orders and prescriptions | medication[x], subject, dosageInstruction |
| AllergyIntolerance | Allergies and reactions | code, patient, reaction, criticality |
| DiagnosticReport | Lab or imaging report summaries | code, status, result, issued |
| Bundle | Grouped resources for transport | type, entry, total |
Common Validation Errors
Common FHIR JSON errors include malformed JSON, missing resourceType, fields on the wrong resource, invalid date formats, values placed in the wrongvalue[x] field, references that point to missing resources, and Bundles with incorrectly shaped entries.
For deeper interoperability work, compare standards in the FHIR vs HL7 guide, decode source messages with the HL7 parser, or inspect clinical document sources with the CCDA viewer.
Frequently Asked Questions
What is a FHIR validator?
A FHIR validator checks whether a FHIR JSON resource has valid JSON syntax, a recognized resourceType, expected fields, and a structure that matches the selected FHIR resource type.
Which FHIR resources can I validate?
You can inspect common FHIR JSON resources including Patient, Observation, Encounter, Condition, MedicationRequest, AllergyIntolerance, Procedure, DiagnosticReport, and Bundle.
Does this replace a full implementation guide validator?
No. This tool is designed for fast browser-based inspection. Production systems should also validate against official implementation guides, profiles, terminology rules, and server-side conformance requirements.
Is FHIR validation done in the browser?
Yes. The tool runs client-side in the browser, which helps reduce exposure because the resource does not need to be uploaded to a remote parsing service.
How does FHIR relate to HL7 v2?
HL7 v2 is a pipe-delimited messaging standard used heavily inside hospitals. FHIR is a resource-based API standard that commonly uses JSON and REST. Many modern projects map HL7 v2 messages into FHIR resources.