The FHIR terminology server for SNOMED CT, LOINC, ICD and every other code system, in one binary.

Documentation · Quick start · What ships today · Licensing

Project

Quality and security

Conformance and compliance

What FerroTERM does

Health records are full of codes. A diagnosis is a SNOMED CT or ICD code, a lab result a LOINC code, a medicine a code from a national drug database. These code systems (the shared lists of medical terms) are what let two systems agree that they mean the same thing. Every application that records or exchanges clinical data needs to look codes up, check them and search them.

FerroTERM answers those questions for every application at once. It loads the code systems you are licensed for and serves them over FHIR, the standard interface health software uses for terminology: look up a code, check that a code belongs to a list, find every narrower term, translate a code from one system to another. It runs as one program, with no database or search engine to operate beside it.

Who it is for

• Hospitals and national eHealth programmes that need one terminology service for all their applications.
• Software vendors and integrators that need SNOMED CT, LOINC or ICD in their products without running a heavy terminology stack.
• Terminology teams that edit and publish value sets (curated lists of codes) in the console.

Why you can trust what it claims

Every release is signed and comes with a software bill of materials (the list of every component inside) and SLSA build provenance, so you can check that what you install is what was built here. The source is public, and every feature is in this repository: there is no paid edition with extra functions. The conformance badges come from the HL7 terminology test suite, run against every change, with a committed pass list per FHIR version, so you can check a result against the standard yourself.

Part of FerroHEALTH

FerroTERM is one of five FerroHEALTH servers. Each does one job and reaches the others only over published standards: FerroEHR stores the record, FerroBRIDGE translates it to FHIR and the OMOP research model, FerroFED connects records across organisations and borders, FerroPIX matches patient identities, and FerroTERM serves the code systems. Any FHIR client can use FerroTERM, not only the FerroHEALTH products. Sign-in, the audit trail and the web consoles come from three shared libraries: FerroAUTH, FerroAUDIT and FerroUI.

Quick start

The image serves UCUM, BCP 47, BCP 13 and ISO 3166-1 with no configuration, so the first call needs nothing beyond Docker:

docker run --rm -p 8080:8080 ghcr.io/ferrohealth/ferroterm:0.4.1

In a second terminal, look up a unit of measure:

curl 'http://localhost:8080/r4b/CodeSystem/$lookup?system=http://unitsofmeasure.org&code=mg/dL'

A clinical code system such as SNOMED CT is a release you hold a licence for. ferroterm-build, in the same image, turns it into an index once, and the server reads that index at startup. Install and run and loading code systems continue from here.

What it serves

SNOMED CT, LOINC, UCUM, BCP 47, BCP 13, ISO 3166-1, ICD-10 (WHO), ICD-10-NL, ICD-10-CM, ICD-11 MMS, ICD-11 ICF, ICD-11 Foundation, ATC/DDD, ICPC-2, RxNorm, the DHD Diagnosethesaurus and Verrichtingenthesaurus, the G-Standaard, the Nederlandse Labcodeset, the NHG ICPC-1 to SNOMED CT map, and any FHIR CodeSystem, ValueSet, and ConceptMap resources (HL7 Terminology's 900+ systems load this way).

The code systems page lists, per system, the versions handled, the build command and the licence position. You bring the release you are licensed for; UCUM and the registries are built in.

What ships today

Terminology

• The FHIR terminology API: $lookup, $validate-code, $subsumes, $expand, $translate and $closure
• FHIR R4, R4B, R5 and the R6 ballot, each in its own version's shapes, in JSON and XML
• Value sets, implicit value sets and ECL, the SNOMED CT expression language
• Stored value sets, code systems and concept maps with history, when you name a database

Operations

• The console: browse, look up, expand and translate, and compose value sets
• Syncing from a national terminology service, one way into a running server
• Health, metrics and request identifiers, and hardware sizing
• Verifiable releases: images for amd64 and arm64 and release binaries, signed, with a software bill of materials

Libraries

• The SNOMED CT, LOINC, ICD, RxNorm and Dutch release readers and the terminology engine, published as Rust crates (listed below)

Speed and footprint, measured per code system

Code system	Release	Concepts	Build	Peak build memory	Index on disk	Resident	$lookup	$validate-code	$subsumes	$expand (small)	$expand (large)	Search	Snowstorm
ICD-10-CM	2026	98,827	1.51 s	359 MB	44 MB	91 MB	105 µs	60 µs	58 µs	n/a	n/a	n/a	not run
ICD-10-NL	2021	42,769	880.52 ms	221 MB	21 MB	66 MB	96 µs	60 µs	64 µs	n/a	n/a	n/a	not run
ICD-11 MMS	2026-01	37,211	n/a	n/a	44 MB	99 MB	138 µs	59 µs	n/a	129 µs	116 µs	139 µs	not run
LOINC	2.83	257,266	8.15 s	2.54 GB	310 MB	440 MB	136 µs	56 µs	n/a	126 µs	7.23 ms	283 µs	not run
RxNorm (prescribable subset)	09082026	81,468	4.58 s	667 MB	77 MB	133 MB	388 µs	114 µs	n/a	n/a	n/a	n/a	not run
SNOMED CT (International edition)	20260901	535,502	14.12 s	3.06 GB	559 MB	943 MB	217 µs	66 µs	59 µs	215 µs	1.7 ms	353 µs	not run
SNOMED CT (Netherlands edition)	20260630	548,949	17.66 s	3.88 GB	864 MB	1.14 GB	222 µs	66 µs	59 µs	285 µs	2.28 ms	817 µs	not run

Warm p50 over 200 HTTP round trips on one machine (Apple M2, 17.18 GB, macos/aarch64), FerroTERM 0.1.4 serving FHIR R4B, taken 2026-09-22. The records are under bench/records/; the benchmarks page has the method, the cold and tail latencies, and how to reproduce a record.

Published crates (14)

Crate	What it does	Version	Docs	Downloads
rf2	The SNOMED CT RF2 release loader and typed component model (Apache-2.0)
concept-graph	The SNOMED CT ontology as CSR adjacency and roaring transitive-closure bitmaps
concept-store	The disk-backed columnar concept and description store
designation-index	The fst and roaring description search index
sct-ecl	The SNOMED CT Expression Constraint Language lexer, parser and evaluator
sct-scg	The SNOMED CT Compositional Grammar lexer, parser and printer
loinc	The LOINC release loader and typed row model
classification	The ClaML and ICD-10-CM tabular readers into one classification model
dhd-thesaurus	The DHD Diagnosethesaurus and Verrichtingenthesaurus reader
gstandaard	The G-Standaard (Z-Index) product ladder reader
labcodeset	The Nederlandse Labcodeset publication reader
icd11	ICD-11 entities from the WHO ICD-API local deployment, cached and read
rxnorm-rrf	The RxNorm Rich Release Format reader and typed row model
fhir-terminology	The FHIR terminology operations over the code system provider seam

Learn more

• Documentation and the FerroHEALTH book
• What FerroTERM is, architecture at a glance and how it compares
• Conformance and benchmarks
• Changelog and milestones
• Security policy
• Contributing, code of conduct, support, governance, maintainers and the AI statement

Licence

Business Source License 1.1 (LICENSE), with Apache License 2.0 as the Change License four years after each version; the rf2 crate is Apache-2.0 today. The code systems keep their own licences, and the licensing page says when you need a commercial licence from Cadasto B.V.