1 · Read
Short lessons, in the right order
48 lessons, from “what is HL7” to FHIR. About ten minutes each.
Signal received · ORU^R01 · 28.5 /h
Learn HL7 by touching it.
A real hospital message in front of you. Click a field, it explains itself. Free, in English and French, by someone who has been wiring these exchanges since 2013.
No account, no credit card. Click the message to try.
labo-sommeil → dossier-patientMLLP · 2575
MSH|^~\&||LELEUX|HIS|LELEUX|20260627|||MSG001|P|
PID|1|||||||F
OBR|1||PSG-2026-0042||||20260626
OBX|1|NM|||||<5||||F
OBX-5type NM
Observed value
28.5 per hour. With OBX-8 set to H, the record knows it is above normal: moderate apnea.
FHIR → Observation.valueQuantity
How it works
Read. Touch. Check. Three moves, and HL7 becomes readable.
2 · Touch
Every example is alive
No frozen screenshots. Click, edit, and see the FHIR equivalent.
3 · Check
A quiz, badges, your progress
Each lesson ends with a few questions. You always know where you stand.
The lab · transport
Watch the message leave, travel, and come back with its acknowledgement.
Sender
Sleep lab
The polysomnography software finishes the report.
Receiver
Patient record
Files the result and replies “got it”.
The path
From zero to integration, with no gaps.
8 modules, 48 lessons, about 9 hours. In the order every serious course follows, without the price tag.
See the full path- MODULE 01 · 4 lessonsThe foundationsWhy hospital software must talk, and what HL7 really is.
- MODULE 02 · 9 lessonsReading an HL7 v2 messageSplitting rules, the header, data types and codes. After this, you can read any message.
- MODULE 03 · 9 lessonsMessage typesAdmissions, orders, results, documents, appointments: the whole family.
- MODULE 04 · 5 lessonsTransport and acknowledgementsHow a message actually travels, and how we know it arrived.
- MODULE 05 · 8 lessonsThe integrator’s jobRead a spec, map two systems, test, troubleshoot, go live.
- MODULE 06 · 6 lessonsFHIRThe modern standard: resources, JSON, web APIs. And how it lives next to v2.
- MODULE 07 · 1 lessonThe full caseOne night at the sleep lab, from the order to the result in FHIR.
- MODULE 08 · 6 lessonsPatient monitoringVital signs every minute, several devices, alarms, MDC codes: HL7 in intensive care.
The lab
Tools for your actual job, not just for the course.
ExplorerA message with every field clickable, explained plainly with its FHIR equivalent.BuilderBuild a message field by field, with live validation.DebuggerPaste the message from work: we break it down and spot what is wrong. Nothing leaves your browser.ReferenceAll 149 HL7 v2.5.1 segments and their fields, searchable instantly.
Why free
HL7 basics should be open to everyone.
Free, for real
The whole path is open, no account, no credit card. The basics should never be a barrier.
Interactive, not slides
You learn by handling real messages, not by staring at dead screenshots.
Checked, not copied
Every field and data type is checked against official HL7 sources before it goes live.
The story
A 2013 final-year project, finally finished.
In 2013, my final-year project set out to make HL7 understandable. Since then I have wired medical software into hospitals, and I have often had to explain the same basics to colleagues who were just starting out. So I am rebuilding it, better, and giving it away.
Andy Leleux
Sleep technologist, medical electronics graduate, proud geek
- 2013The project“A teaching approach to HL7”: a networked mock-up that carried a real admission message from the front desk to the ward.
- 2013 → 2026The fieldMedical software rollouts, HL7 interfaces, the sleep lab.
- 2026LearnHL7Free, bilingual, interactive. For everyone landing in healthcare integration.
Frequently asked questions
Do I need to code?
No. An HL7 v2 message is text split by a few characters. If you can read a table, you can read a message. Code only comes in when you automate, and that is not what the path is about.
HL7 v2 or FHIR: which one should I learn?
Both, in that order. v2 still runs the vast majority of hospital exchanges today. FHIR is arriving alongside, mostly for web and mobile apps. The path starts with v2 and ends with FHIR.
Is it really free?
Yes. No trial, no credit card. Free accounts will come, to find your progress on all your devices.
Do the examples come from real patients?
No. Every patient, facility and number is made up. The “Leleux Clinic” does not exist. The situations, however, come from the field.
Can I paste a message from work?
Yes, in the Debugger. The analysis runs in your browser: nothing is sent anywhere. Still, anonymize patient data before sharing it with anyone.
Your first message decoded in five minutes.
Free. No account to start. No needless jargon.
Start the path