Tools & Resources
... for coding and verification
International Classification of Health Interventions (ICHI)
The official WHO browser for the complete ICHI classification. Browse all Action, Target and Means axis elements, view pre-coordinated stem codes, and explore the full hierarchy of health intervention categories.
Open ICHI Browser ↗ICHI Reference Guide
The official coding rules and guidelines published by the WHO. The Reference Guide defines how Action, Target and Means elements may be combined, how extension codes are applied, and how post-coordinated codes are constructed. This is the authoritative rule set that CodAs follows for every coding request.
Download Reference Guide (PDF) ↗ICHI Stem Code Verification
An independent verification tool for WHO ICHI pre-coordinated stem codes, hosted at verify.ichi.codes. Enter any stem code to check whether it exists in the official WHO dataset and to review its definition, inclusions, exclusions and index terms.
How CodAs and the verification tool work together
CodAs and the verification tool serve fundamentally different purposes and operate on different data:
CodAs is a generative coding assistant. It constructs post-coordinated ICHI codes from free-text descriptions – combining Target, Action, Means and extension codes according to the rules in the ICHI Reference Guide. CodAs does not look up codes in a database; it builds them compositionally from the ICHI vocabulary.
verify.ichi.codes is a lookup tool. It searches the official WHO dataset of 10,418 pre-coordinated stem codes – the codes that the WHO has explicitly defined and published. It confirms whether a given stem code exists and displays its official definition.
This separation is deliberate. CodAs generates codes without access to the pre-coordinated database, relying solely on the ICHI vocabulary and coding rules. The verification tool then allows users to check the generated stem codes against the official dataset – providing an independent quality check.
Automatic stem code links in CodAs
After every coding result, CodAs automatically extracts all stem codes
(format: XXX.XX.XX) from the response and displays them
as clickable verification links. These links appear both above and below the response. Because coding
results can be extensive – often spanning several screens – this ensures
that the verification links are always within reach, regardless of the
user's scroll position.
Clicking any stem code opens verify.ichi.codes in a new tab with the code already entered in the search field.
ICHI stem codes (e.g.
KBP.AE.AD) represent the core
intervention: Target · Action · Means. The WHO publishes these as
pre-coordinated entries with official definitions.
Extension codes (joined by &), intervention bundles
(joined by +), and interventions performed together
(joined by /) are post-coordinated constructions –
they are assembled according to ICHI rules but are not individually
listed in the WHO dataset. Therefore, only the stem code components
can be verified against the official database.An independent research tool based on WHO ICHI data, used under the terms of the WHO-FIC licence.