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XML Is Not Dead: Why Enterprises Still Rely on It

Despite the JSON revolution, XML remains entrenched in healthcare, finance, and government systems. Here's why — and what to do about it.

October 22, 2024·5 min read·Try the XML Formatter →

The Premature Death of XML

Around 2010, developers started declaring XML dead. JSON had arrived, REST had displaced SOAP, and the web development community moved on. Today, new APIs are built in JSON. New microservices speak JSON. The startup world has largely never touched XML.

But in regulated industries — healthcare, finance, government, telecommunications — XML never left. It didn't lose the argument. It simply wasn't the kind of technology you can replace by declaring a winner on a blog.

Where XML Is Entrenched

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Healthcare

HL7 v2, HL7 v3, CDA, FHIR XML

Clinical document exchange between hospitals, labs, pharmacies, and payers is built on HL7 standards that predate JSON and are embedded in decades of certified EHR software. HL7 FHIR offers a JSON representation, but XML FHIR remains the primary format in many deployments.

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Financial Services

FIXML, FpML, XBRL, ISO 20022

Securities trading (FIXML), derivatives (FpML), regulatory reporting (XBRL), and modern payment messaging (ISO 20022) are all XML-based. ISO 20022 alone underpins SWIFT, TARGET2, and most central bank payment systems globally.

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Government & Defense

NIEM, UCORE, DoD DISR

The National Information Exchange Model (NIEM) is used across US federal, state, and local agencies for inter-agency data sharing. Military and intelligence systems have XML-based data exchange standards that span decades of infrastructure.

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Telecommunications

SOAP, WSDL, ebXML, OMA

Telecom OSS/BSS systems, provisioning interfaces, and billing platforms were built on SOAP/WSDL in the early 2000s and remain in production. Replacement is measured in years, not sprints.

What XML Gets Right

XML's persistence isn't nostalgia. Several of its features remain genuinely useful in enterprise contexts:

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Namespaces: XML namespaces allow multiple vocabularies to coexist in a single document without collision — critical for standards like SOAP that compose multiple schemas.
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Schema validation (XSD): XML Schema Definition provides strict contract validation with type checking, value constraints, and complex relationship rules. JSON Schema exists but XSD has decades more tooling and is embedded in certification requirements.
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XSLT transformations: XSLT is a turing-complete transformation language for XML. The combination of XML + XSLT allows data transformation pipelines without writing code — a significant operational advantage in regulated environments.
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Mixed content: XML can contain both structured data and inline text (like HTML) in the same document. JSON cannot represent this without hacks.

Working With XML in 2024

If you're a developer in a modern stack who needs to interface with XML-heavy enterprise systems, a few pragmatic approaches help:

1Use an XML formatter to make unreadable payloads legible before debugging
2Convert XML to JSON at the boundary of your system and work in JSON internally
3Validate against the published XSD before sending — invalid XML is rejected upstream without useful error messages
4Prefer libraries with proper namespace support (libxml2, lxml, JAXB) over minimal parsers

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