JSON, or JavaScript Object Notation, is a lightweight data interchange format that has become the de facto standard for transmitting structured data on the web. Originally derived from JavaScript, JSON is language-independent and supported by virtually every programming language and platform. Its simple syntax of key-value pairs, arrays, and nested objects makes it both easy for humans to read and write and efficient for machines to parse and generate.
In healthcare informatics, JSON has emerged as the preferred format for FHIR resources. While FHIR supports both JSON and XML representations, JSON has become dominant in practice due to its smaller payload size, faster parsing, and alignment with modern web development practices. A FHIR Observation resource in JSON clearly represents a lab result with nested structures for the code (LOINC), value (numeric with UCUM unit), reference range, and interpretation — all in a format that any developer can understand at a glance.
The adoption of JSON in healthcare represents a significant shift from the industry's historical reliance on complex, verbose formats. Earlier standards like HL7 v2 used pipe-delimited segments, while HL7 v3 and CDA relied on heavily namespaced XML schemas that were notoriously difficult to work with. JSON's simplicity has lowered the barrier to entry for healthcare application development, enabling a new generation of startups, open-source projects, and innovation in health IT.
For lab report digitization, JSON is the natural output format. When an OCR pipeline processes a lab report and produces structured FHIR data, that data is serialized as JSON for transmission via REST APIs, storage in databases, or import into EHR systems. The readability of JSON also makes it valuable during development and debugging — a developer can inspect a FHIR Bundle containing a digitized lab report and immediately understand its structure, verify that LOINC codes are correct, and validate that values and units are properly formatted.