Blaze: A High-Performance Open Source FHIR Server with Embedded CQL Evaluation Engine

Kiel A, Kussel T, Gründner J, Overton P, Ganslandt T, Lablans M (2026)

Publication Type: Journal article

Publication year: 2026

Journal

Studies in Health Technology and Informatics IOS Press

Book Volume: 336

Pages Range: 1481-1485

DOI: 10.3233/SHTI260455

Abstract

Blaze is an open-source, high-performance FHIR server with an embedded Clinical Quality Language (CQL) engine, initially developed to support large-scale federated feasibility queries in the German Cancer Consortium (DKTK) and later extended in the German Medical Informatics Initiative (MII) and other research consortia. Built in Clojure, Blaze uses a functional, immutable database architecture based on RocksDB to enable lock-free concurrency, full resource history, and efficient query execution. Our benchmarks on datasets exceeding one billion FHIR resources show that it supports cohort queries over millions of patients in under one minute. Deployed in production at over 60 national and international research sites, Blaze demonstrates that a functional, embedded database design can achieve scalable, standards-compliant performance for clinical research data networks.

Authors with CRIS profile

Julian Gründner Lehrstuhl für Medizinische Informatik Thomas Ganslandt Lehrstuhl für Medizinische Informatik

Involved external institutions

Universität Leipzig DE Germany (DE) Deutsches Krebsforschungszentrum (DKFZ) DE Germany (DE) TMF – Technologie- und Methodenplattform für die vernetzte medizinische Forschung e.V. DE Germany (DE)

How to cite

APA:

Kiel, A., Kussel, T., Gründner, J., Overton, P., Ganslandt, T., & Lablans, M. (2026). Blaze: A High-Performance Open Source FHIR Server with Embedded CQL Evaluation Engine. Studies in Health Technology and Informatics, 336, 1481-1485. https://doi.org/10.3233/SHTI260455

MLA:

Kiel, Alexander, et al. "Blaze: A High-Performance Open Source FHIR Server with Embedded CQL Evaluation Engine." Studies in Health Technology and Informatics 336 (2026): 1481-1485.

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