Open Client Registry (OpenCR)

Open Client Registry (OpenCR) is an open-source patient identity service for connecting records across health information systems. It fits health organizations and technical teams that can adapt and operate their own registry infrastructure. The trade-off is clear: strong matching and standards support come with substantial deployment and security responsibilities.

Overview

OpenCR creates a shared identity layer for care coordination, continuity of care, and reporting. It can assign and find unique identifiers and receive FHIR messages from point-of-service applications such as laboratories and electronic medical records. This is an identity registry, not a shared health record: clinical information is outside its scope, and the documented implementation does not allow source systems to retrieve patient demographic data from the registry.

The project is open source, based on open standards, and presented as a community project for adaptation to local use cases. IntraHealth International developed it with USAID support through the MEASURE Evaluation project, with input from stakeholders in Uganda and technical teams at CDC and USAID. That background makes it relevant to public-health and interoperability programs, but it does not turn the software into a managed, turnkey service.

Key features

Configurable identity matching

OpenCR combines deterministic and probabilistic methods and offers multiple algorithm variations through a hybrid matching approach. Teams can therefore tune linkage behavior for their data rather than accept a single fixed rule set. Its interface shows records and allows an operator to break an incorrect match, a valuable safeguard when automated decisions need human correction. This flexibility is most useful where several facilities have different data quality or identifier practices; it also means implementation teams must define and govern their matching policy.

FHIR exchange and identifiers

The service accepts FHIR messages from systems at the point of care and supports real-time API use as well as batch file import. The documented stack includes the OpenCR Service and HAPI FHIR Server, with OpenSearch or Elasticsearch for search; OpenHIM can be added when an interoperability layer is needed. These standards-based connections suit organizations already building around FHIR R4, while the multi-component architecture adds integration and operations work.

Audit and access controls

Queries and other transactions are retained as audit events in HAPI FHIR and are visible in the OpenCR UI, giving administrators a way to review registry activity. Security guidance calls for TLS, restricted access to services and the interface, changed default passwords, and authenticated users and nodes. OpenCR does not supply JWT or another complete user-authentication solution out of the box, so each deployment must add and maintain its own approach.

Pricing

OpenCR is free and open source, with no subscription charge. That removes licensing cost for organizations able to run the software themselves, but infrastructure, database, integration, and administration work remain operational commitments. There are no paid tiers or included service levels to buy in place of that work.

Platforms

OpenCR is offered for API, web, Linux, macOS, Windows, and self-hosted use. Production guidance expects Linux, command-line familiarity, and Linux administration expertise. HAPI FHIR requires a production database backend, with PostgreSQL and MySQL given as examples. The local installation guide, including a modern CPU and 8GB of RAM, is intended for demonstrations or tests rather than production, so a pilot setup should not be mistaken for a deployment specification.

Who it's for

Choose OpenCR when a health program needs a dedicated patient identity layer, FHIR-based exchange, configurable linkage, and an auditable workflow that it can operate itself. It is a particularly good fit for interoperability teams, public-health programs, and implementers adapting an open project to local systems. It is a poor fit for organizations seeking a hosted registry, built-in end-user authentication, a clinical data store, or a simple way for source systems to read demographics back from the registry.

Pros and cons

Pros

• Flexible matching: deterministic, probabilistic, and hybrid options accommodate varied data and linkage policies.
• Standards-oriented exchange: FHIR R4 support, APIs, and batch import connect point-of-service systems.
• Human correction and audit: staff can break matches, while transactions remain visible as audit events.
• No license fee: open-source distribution supports adaptation without subscription pricing.

Cons

• Operational burden: production requires Linux administration, command-line skills, and a database service.
• Authentication gap: user authentication, including JWT-based options, must be supplied by the deployment.
• Narrow data role: it does not store clinical data and the documented implementation does not return demographics to point-of-service systems.
• Distributed architecture: HAPI FHIR, search infrastructure, and optional OpenHIM create more components to secure and maintain.

Alternatives

Browse the broader Identity Resolution Software category when you want to compare more identity-linkage approaches.

• InterSystems IRIS is the better choice for a paid platform with a free Community Edition, free trial, and broad API, desktop, web, and self-hosted coverage.
• Splink suits teams wanting a free open-source Python package installed with pip or conda rather than a complete registry service.
• Hightouch is preferable for managed API and web synchronization, including a free tier with two active syncs and hourly frequency.
• pyJedAI is a free open-source library with no paid plans or stated usage limits.
• Zingg is worth considering for open-source batch probabilistic matching across millions of records, with an enterprise option for batch and real-time use.
• AWS Entity Resolution fits teams wanting a paid cloud data service billed per 1,000 records, with provider-license costs applying to provider matching.
• NVECTA is an alternative paid identity-resolution product available through API, web, Android, and iOS.
• Senzing Entity Resolution targets organizations prepared for commercial subscription pricing, including a listed $58,560-per-year 10M-DSR plan.

Verdict

OpenCR is a strong choice for technically capable health and public-health teams that need open, FHIR-connected patient identity matching with manual correction and audit visibility. Choose it for control, adaptability, and zero license cost. Look elsewhere if you need hosted operations, built-in authentication, clinical records, or a simpler production path.