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Coordinated Access System

Supporting Coordinated Access to housing for people who are homeless can pose procedural and logistical challenges to communities. The Open Path Coordinated Access System (CAS) is a tool that facilitates matching individuals with housing opportunities, and supports the intra-agency communication necessary for successful move-in. As a stand-alone system, or tightly integrated with the Open Path HMIS Warehouse, the Open Path CAS brings structure and efficiency to an often complicated process.


The Open Path CAS is a tool for communities to match homeless individuals with available housing assets in a way that:

  • Provides transparent logic for individual and housing prioritization.
  • Handles the communications and logistics of coordinating a successful move-in.
  • Preserves client privacy while meeting data confidentiality laws.
  • Can be used as a standalone system or integrated with HMIS.

Originally developed for the City of Boston as a way to eliminate chronic homelessness, the Open Path CAS is open source licensed, and can be downloaded and used for free by any community. Green River also provides a fully hosted installation, user support, and custom feature development.

About our work with Boston:
The story behind the Open Path Coordinated Access System and our work for Boston
Creating innovative software for Boston's Way Home, November 2016
Boston Puts Tech to Use in Ending Homelessness Spare Change News, March 2016


When a housing vacancy arises (either a voucher or physical unit), Open Path CAS generates a prioritized list of eligible people. A user with permission can manage the organization of service programs, funding sources, and specific project units—each of which can have eligibility criteria. This function allows housing opportunities that come from a given funding source to be limited to veterans, for example, or women under 25 years old.

When a housing opportunity is marked available, the system identifies currently homeless people who meet the preset eligibility rules. It then prioritizes that list based on several factors and suggests who might best fit that particular housing chance. This prioritization logic can be customized in a variety of ways: to reflect how a community prioritizes housing; for legal restrictions; to account for the available data; to weight the length of homelessness, or degree of "chronicity" or vulnerability; the size of the eligible population; and even the predicted chance of long term success.

In an ideal world, a CAS can be used to identify the best match by incorporating readily available data. The complex reality is that the full context of someone's circumstances often is not documented rigorously within a database system. In these cases, the Open Path CAS streamlines the process by providing a list of potential matches, based on the available data to develop a prioritized list, from which someone—a housing navigator, say—can select.

Matches in Progress


Much of the coordination of Coordinated Entry housing services is communication between people. Once a housing match is selected, Open Path CAS provides a (customizable) email-based workflow to bring everyone—the homeless individual, municipal staff, service provider administrators, caseworkers—into the process. Notifications containing time-expiring links provide status information and decision making capability without exposing personal identifiable information. The system also has overrides to prevent a non-responding party from delaying a housing process.

User Management

Any number of user roles can be defined with highly granular permission settings.

Manage Roles

The Open Path CAS is designed to integrate fully with HMIS. Depending on the functionality available in your specific HMIS, Open Path CAS can get all client record details from one or more HMIS installations, using whatever data exchange facilities are available (API calls, scheduled export files, direct SQL queries). If a data import routine doesn't currently exist for a specific HMIS, we can usually create one easily. The system includes both automatic and human-mediated record de-duplication, to handle client records from multiple HMIS systems, and for when there are duplicate records within an HMIS. It also provides forms for adding and managing records directly.


To operate effectively, Open Path CAS needs to contain personal identifiable information and often some medical diagnosis information. The system is designed to comply with the HIPAA Security Rule, and encourage user best practices. 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, Open Path CAS 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").

Diagram of the Coordinated Access System


The Open Path Coordinated Access System (CAS) 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 CAS on GitHub

On Creating Innovative Software for Boston's Way Home