HL7 v2 utility

HL7 Message Diff & Comparison Tool

Compare two HL7 v2 messages and find meaningful changes by segment, field, repetition, component, and subcomponent.

Compare messages Open formatter Inspect FHIR JSON

Structured differences:

PID.11.1
12 SAMPLE STREET
→ 24 UPDATED ROAD

OBX.5
6.2 → 7.4

+ OBX · C reactive protein

Privacy reminder. Do not paste real patient data, credentials, secrets, production identifiers, or confidential messages. Use synthetic/test HL7 only.

Comparison

Paste two HL7 messages

The comparison runs locally in your browser. Repeating segments such as OBX, AL1, DG1, NK1, IN1, and NTE are matched using useful identifiers where available instead of line position alone.

Original message

Baseline or before version.

Updated message

Changed or after version.

Comparison options

Ignore MSH.7 timestamp Ignore MSH.10 control ID Ignore trailing empty fields Ignore whitespace differences Case-sensitive comparison Compare decoded HL7 escapes Show unchanged values

Additional ignored fields

Separate field paths with commas or spaces.

A differences-only report will appear here.

FAQ

HL7 comparison questions

How are repeating segments matched?

The tool uses identifiers appropriate to common segments, such as the observation identifier for OBX, allergen for AL1, diagnosis code for DG1, and order numbers for ORC and OBR. It falls back to occurrence order when no reliable identifier is present.

Why are MSH.7 and MSH.10 ignored by default?

Message timestamps and control IDs commonly change between otherwise equivalent messages. You can include them by clearing the options.

Is this a certified HL7 validator?

No. It is a practical comparison utility for development, testing, troubleshooting, and documentation.

Can I paste real patient data?

No. Use synthetic, anonymised, or test data only.