Open Client Registry (OpenCR)

Open Client Registry (OpenCR) is an open-source patient identity registry for connecting health information systems. It best suits health organizations and technical teams prepared to adapt and operate their own deployment. Its matching and FHIR capabilities are focused, but production operation requires Linux administration and additional security work.

Overview

OpenCR links patient identities across systems to support care coordination, continuity of care, and reporting. It can assign and look up unique identifiers and accept FHIR messages from point-of-service systems such as labs and EMRs. It is not a shared health record: it holds no patient clinical data, and the documented implementation does not let point-of-service systems retrieve patient demographics from the registry. Organizations needing a source for clinical records or a two-way demographic lookup should choose a different component.

Developed by IntraHealth International with USAID support through MEASURE Evaluation, OpenCR is an open-source, open-standards community project intended for adaptation. That makes it a fit for teams building a registry around their own use case, rather than buyers seeking a turnkey managed service.

Key features

Configurable identity matching

OpenCR supports probabilistic and deterministic methods, multiple algorithm variations, and a hybrid approach. This gives implementation teams options for tuning how records are linked; the UI also lets users view records and break matches, offering a manual correction route when an automated link needs intervention.

FHIR exchange and audit events

FHIR R4 is part of the documented deployment, and OpenCR accepts FHIR messages from point-of-service systems. Transactions, including queries, are stored as audit events in HAPI FHIR and can be viewed in the UI. That provides an audit trail within the registry architecture, while the lack of demographic retrieval from point-of-service systems remains a meaningful constraint on integration patterns.

Deployment components and security

The documented stack combines the OpenCR Service, HAPI FHIR Server, and either OpenSearch or Elasticsearch; OpenHIM is optional. Production HAPI FHIR requires a database backend, with PostgreSQL and MySQL given as examples. Security guidance calls for restricting UI and service access, using TLS, changing default passwords, and securing user and node access. JWT and other user authentication solutions are not included out of the box, so deployments must add an authentication solution and account for that work.

Pricing

OpenCR is free and open source, with a free plan. There is no paid tier described, so the software itself avoids a license charge; the trade-off is that teams must provide and operate the production environment, including Linux administration and database infrastructure.

Platforms

OpenCR supports API, Linux, macOS, self-hosted, web, and Windows environments. The production installation guide expects Linux, command-line familiarity, and Linux administration expertise, so the broad platform coverage should not be read as a low-effort production setup. The local installation guide is for demonstrations or tests, not production, and gives a modern CPU with 8GB RAM among its prerequisites.

Who it's for

OpenCR is most appropriate for health organizations and technical teams integrating patient identity across systems that exchange FHIR messages and can maintain a self-hosted deployment. Its configurable matching, identifier service, and manual match correction address registry work without duplicating clinical records. It is a poor fit for organizations that need a shared clinical record, demographic retrieval by point-of-service systems, turnkey hosting, or authentication built in.

Pros and cons

Pros

Probabilistic and deterministic matching with multiple variations lets implementation teams tune identity linking to their deployment.

FHIR message acceptance and unique identifier assignment support registry integration with point-of-service systems.

Users can inspect records and break matches, providing a manual path to correct problematic links.

Transactions, including queries, become viewable audit events in HAPI FHIR.

Free, open-source licensing avoids software fees and supports adaptation by community projects.

Cons

It stores no clinical data and does not provide demographic retrieval to point-of-service systems, limiting its role to identity registry functions.

Production calls for Linux expertise, command-line familiarity, and a database backend, which raises operational demands for smaller teams.

User authentication such as JWT must be added separately, alongside the recommended TLS and access restrictions.

The local installation guide is for demonstrations or tests, not production, so it is not a shortcut to a live deployment.

Alternatives

Identity Resolution Software is a useful place to compare other options. Choose InterSystems IRIS if its paid platform and free Community Edition or free trial better suit your deployment. Consider Senzing Entity Resolution if you want a paid entity-resolution product with a free plan and trial. Hightouch is a freemium API and web option; its Free plan includes 2 active syncs per month, hourly sync frequency, and 100,000,000 operations per month, while Self-serve includes 10 active syncs per month and hourly sync frequency.

For an open-source alternative, Splink is a free Python package installed via pip or conda, with Linux, macOS, self-hosted, and Windows platforms. Treasure AI Composable CDP is a paid option for Android, API, iOS, and web, with custom pricing and warehouse credits applying to query execution. NVECTA is another paid option for Android, API, iOS, and web. pyJedAI is a free open-source library with no paid plans or usage limits stated. Zingg offers a free open-source Community edition for batch probabilistic matching across millions of records, with enterprise support for batch and real-time use.

Verdict

Choose OpenCR if your health organization needs an adaptable, free patient identity registry with configurable matching and FHIR message acceptance, and has the technical capacity to run Linux production infrastructure. Its strongest case is focused registry functionality without a software license fee. Look elsewhere if you need clinical records, demographic lookup from point-of-service systems, or authentication and production operations supplied as part of a managed product.