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Healthcare organizations and stakeholders are focusing more on healthcare interoperability to optimize and improve patient care. HL7 interface engines provide the solution for healthcare applications needing to exchange, share, and process data between systems. Healthcare interface engines use standards such as HL7 and data definitions when data is exchanged between applications via mapping and data transferring. 

Open source HL7 Software is starting to take over healthcare data centers as it provides a competitive option to proprietary technology products. For organizational-level licenses (e.g., hospitals, clinics, laboratories, etc.), proprietary interface engines start at a few hundred dollars and cost hundreds of thousands of dollars.

Different Types of Open Source HL7 Software

There are multiple HL7 interface engine open sources available for download online. The most popular option is Mirth; however, we will discuss other available choices, their features, and specifications so that you have a detailed guide to the different types of open source HL7 interface engines and what may suit your healthcare organization best. 


The Mirth Project is an open-source HL7 interface software that is created and supported by WebReach. Mirth is a cross-platform that enables the bi-directional exchange of HL7 messages between applications and systems over multiple modes of transport. Mirth is a flexible IT infrastructure that can play various roles using JavaScript and a point-and-click interface to map data elements. Mirth application types include integration platform/ Middleware and processing.

Mirth can be divided into three subprojects:

  • Mirth Match: an open-source plug-in-based master patient index (MPI) that is yet to be available on the market.
  • Mirth Connect: Provides the tools for testing, monitoring, developing, and deploying interfaces. Mirth Connect is specifically designed for the integration of HL7 messages.
  • Mirth Results: Is an open-source clinical data repository that can aggregate and organize clinical information between many sources.

Mirth supported Healthcare data standards:

  • DICOM: This is a standard that supports imaging and messaging between systems and imaging devices. Mirth also supports the National Council for Prescription Drug Programs Script standard.
  • XML: This is Mirth’s original format and includes support for XSLT.
  • HL7 v2 and v3
  • EDI X12: is a general transaction set for insurance and healthcare.
  • Mirth also provides support for PDF and RFT, Javascript Custom connector, Samba, FTP and SFTP, SOAP and TCP, JMS, and MLLP.

Mirth System Requirements:

  • ASP.NET and Java

Mirth has BSD and MPL licenses and has the following databases, Oracle, Apache Derby, PostgreSQL, MySQL, and Microsoft SQL Server.


HAPI (HL7 application programming interface) is an open-source object-orientated HL7 2.x parser for Java. HAPI was initiated by University Health Network over ten years ago and is the closest free alternative to Cloverleaf. Applications that HAPI runs in a clinical setting include clinical documents and lab messaging systems, eMPI systems, and different point-of-service systems.

Requirements to run HAPI:

  • Java Virtual Machine or Java 2 Standard Development (for development)


OpenClinic GA is an open-source integrated hospital information management system and has extensive reporting and statistical capabilities. This integrated system specializes in the management of financial, clinical, administrative, pharmacy, laboratory, and other healthcare data. OpenClinic GA is multilingual and has a GNU LGPLv2.0 license. 

System requirements to run OpenClininc GA:

  • Windows, Linux, or Mac OS 


  • Features:
  • Customizable using java class extensions
  • Statistics on co-morbidity, costs or care, and mortality.
  • Complete ADT management 
  • Unlimited free usage
  • HL7/FHIR API for structured data transfers 
  • LOINC coding supported (total laboratory order entry and result management)
  • 3BT clinical thesaurus with validated coding aid for ICPC-2 and ICD-10. 
  • Snomed CT coding 
  • HRM module 
  • Mobile web interface 
  • WebRTC based module for telecommunication
  • Integration of Weasis/DCM4CHE based DICOM- viewer and PACS solution
  • Pathology and x-ray results management
  • Full scheduling system integration
  • Over 500 global implementations 
  • Focuses on limited resource hospitals
  • Has multimedia (audio, picture, and video) support

PUMA Repository

  • PUMA (Pascal Units For Medical Applications) Repository is a compilation of Pascal units for the support of software development for medical informatics. This open-source interface engine contains reusable source code for a diverse range of application development. The source code includes a support engine for an HL7 engine (compiling, reading, and writing HL7 messages), the EDF and EDF+ (European Data Format), and the conversion of functions for units of measurement.

System requirements:

  • Free Pascal and Lazarus


  • In-built error-handling
  • Reusable code
  • Compatible with Free Pascal/ Lazarus and partly with RAD Studio, Delphi, and other competitors.
  • Demo-applications included
  • Curated by Zenodo, SciScrunch, and OpenAIRE
  • BSD license for commercial projects and FOSS


Opal is a specialist open source and open governance healthcare framework that includes an extensive library of composable modules. The healthcare framework of Opal assists in the fast development of applications. Opal is built on Bootstrap stack, Django, and Angular, ensuring that your application is able to be integrated with other hospital systems such as data inputs and EHRs.

System Requirements:

  • Python and Pip


  • Features:
  • Fast install and start-up time
  • User-friendly configuration to save time
  • Coded reference data
  • Core Clinical reference data implemented as Abstract Subrecords
  • Open RESTful APIs
  • A Full audit trail
  • Applications are configured to provide user management


FreeMED is an open-source medical software specializing in hospital management systems. FreeMED provided an HL7 interface that governs the data transfer between healthcare providers. This hospital management system provides extensive import and export formats, is multilingual, provides support in many languages, and is readily expandable, with developers easily able to customize the system. FreeMED is written in PHP, provides reliable data security, and offers a logical user interface.

System requirements to run FreeMED:

  • Docker

Features of FreeMED include:

  • Document management
  • HL7 interface
  • Self-hosting facilities
  • XML-RPC Backend
  • Modular Architecture
  • Extensible
  • Billing Module
  • Patient Schedule
  • The source code is available in Github.


Open-Source HL7 interface systems are capable of optimizing healthcare organizations’ interoperability capabilities. They provide numerous application development options, are in multiple programming languages, are multilingual, and offer a broad range of features to ensure that you get the HL7 interface engine you need. 

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