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Open Path HMIS Data Warehouse

For communities that utilize multiple HMIS installations, we offer a system that combines detailed client information in one web-based application. The Open Path Warehouse consumes information from any number of HMIS data sources, merges and de-duplicates records, and provides an easy way to access a client's comprehensive service history, view statistics across a CoC, run HUD reports off the entire record set, and monitor data quality community-wide.


The Open Path Warehouse is designed for aggregating records from multiple HMISs. It can help a specific community that has agencies using multiple HMIS systems within a CoC, providing an up-to-date view of individual client situations. And it can be used across a larger geographic region, helping to coordinate services and perform analyses broadly.

The system is designed to:

  • Process client record updates daily from multiple sources.
  • Store information beyond the HUD HMIS specification, including assessments.
  • Support coordinated care efforts, giving service providers a (permissions-managed) view of comprehensive client histories.
  • Identify vulnerable and chronically homeless individuals throughout a community.
  • Generate HUD-required reports.
  • Monitor data quality across multiple agencies.

Originally developed with the City of Boston to support their Coordinated Access efforts and aggregated reporting requirements, the Open Path Warehouse, like our coordinated access system, is open source licensed and can be used for free by any community. Green River can also host an installation, offer end user support, and provide custom feature development.


The Open Path HMIS Warehouse supports multiple ways of gathering data, frequently, with little human interaction. It can download HMIS CSV export files nightly, it can call HMIS APIs for additional data (like assessments, case manager information, and photos), and it can easily be customized to access third-party structured data (like calendar appointments and medication lists). A dashboard provides administrators a clear view of the status of all import processes.

Record merging and de-duplication is sophisticated, and is handled in three ways:

  1. Records that are clear matches, sharing a combination of name, birthdate, and SSN, are automatically merged.
  2. Records that are probable matches, based on statistically calculated similarity, and presented to an administrator for confirmation.
  3. Any two records can be merged (or un-merged) at any time by an administrator.

Merge decisions are preserved indefinitely and are not affected by subsequent data loads. No client information is overwritten during a merge. Rather, multiple records are flagged as one for viewing and reporting.

Suggested Duplicate Clients

Client History

What case managers and service providers know about a client is often limited to what their agency has collected. The Open Path HMIS Warehouse gives those providers a way to see a more complete, holistic client picture – a fundamental tool for managing integrated, coordinated care.

The system can comply with varied data sharing agreements, limiting access by user role. With permission, a case manager might utilize a client's exhaustive housing and shelter history, program registration history, and even medical history to inform care decisions. With up-to-date records, if a client stops frequenting a shelter or program, a case manager can determine if that individual is permanently housed, is safely going elsewhere, or should be a targeted with direct street outreach activity.


The Open Path HMIS Warehouse's dashboards and built-in reporting options realize the broad potential of a centralized data store.

  • Case managers can quickly view critical changes to their clients.
  • Working groups can generate and manage lists of veteran and chronically homeless individuals within a community.
  • Administrators can assess program performance over time.
Nightly Census

Extensive data quality reports help identify gaps and anomalies, and aid in the preparation of federally mandated reports. Current HUD System Performance Measures, AHAR, Veteran AHAR, PIT, and HIC reports are all built in.


Like the Open Path Coordinated Access System, the warehouse system is designed to comply with the HIPAA Security Rule, and safely contain both personal identifying information (PII) and protected health information (PHI). All operations are recorded in audit logs, there are login and password policies in place, and access to private information is limited by user role. If hosted by Green River, the system will be deployed on a HIPAA-compliant Amazon Web Services instance, and all data will be encrypted when stored ("at rest") and during transmission to a user's browser ("in transit").

HMIS Data Warehouse diagram


The Open Path HMIS Data Warehouse is available for free under the GPLv3 license. All enhancements or modifications to the code must be released into the open source, for everyone's benefit.

Green River will provide a hosted solution, configuration assistance, ongoing support, and custom development as desired. Green River managed installations will automatically benefit from all updates created by us, or others, contributed to the main codebase.

Case Study: Boston

Open Path HMIS Data Warehouse on GitHub

On Creating Innovative Software for Boston's Way Home