In an era dominated by lightweight REST APIs and JSON-based communication, XML APIs continue to power some of the most critical digital ecosystems in industries like travel, finance, and healthcare. These industries deal with highly structured data, regulatory constraints, and legacy infrastructure—making XML API integrations not just relevant but essential.
This blog explores the enduring role of XML APIs in these sectors, highlighting how they function, where they are used, and how they contribute to system interoperability, automation, and data standardization.
Understanding XML API Integrations
An XML API Integration involves exchanging structured data between applications using XML (eXtensible Markup Language). It’s commonly used in SOAP (Simple Object Access Protocol) or hybrid services where:
- The data is validated against XSD (XML Schema Definitions)
- Messages must follow strict structural formats
- Both sides need predictable, standardized communication
Key Features:
- Tag-based markup with nested structure
- Schema-based validation
- Platform-agnostic and language-neutral
- Ideal for high-compliance or regulated industries
Why XML Is Still Relevant in 2025
Despite the increasing adoption of modern formats like JSON, XML maintains strong relevance due to:
Structure & Validation
XML supports deep nesting and strict data validation, critical in fields like healthcare records or financial reporting.
Legacy Compatibility
Many established systems, especially in banks and GDSs, were built decades ago and still rely on SOAP/XML interfaces.
Standards & Compliance
International standards (e.g., ISO 20022, HL7) use XML as the foundational format, making it non-negotiable in certain workflows.
XML API Integrations in the Travel Industry
The travel industry relies heavily on XML APIs for everything from search to booking, cancellations, and payments.
Use Cases in Travel:
- Flight and Hotel Booking Systems
Travel APIs from Amadeus, Sabre, Travelport, and Galileo often use XML for communication between agents, portals, and providers. - Passenger Name Record (PNR) Management
Structured XML is used to retrieve, modify, or cancel bookings using unique PNR references. - Dynamic Pricing & Availability
Real-time price fetch, seat maps, and fare rules through standardized XML endpoints. - Car Rentals, Insurance, and Add-ons
Modular XML structures allow third-party service integration.
Benefits in Travel:
- Uniform interface across multiple GDS platforms
- Simplifies partner integration and inventory sharing
- Ensures data accuracy in high-volume systems
- Enables real-time updates on availability and fares
XML API Applications in the Financial Sector
The financial world prioritizes accuracy, auditability, and compliance, making XML a natural fit.
Core Use Cases:
- Bank-to-Bank Communication (SWIFT, SEPA)
The ISO 20022 messaging standard is based on XML and is used for international financial transactions. - Payment Gateways & Invoice Processing
XML is used in ACH transactions, SEPA Direct Debits, and interbank communications. - Regulatory Reporting
Financial institutions report to central banks and regulators using XML-based formats. - ERP System Integration
Systems like SAP and Oracle Financials use XML interfaces to interact with external payment and reconciliation systems.
Benefits in Finance:
- Schema enforcement avoids transaction mismatches
- Highly secure and traceable messaging
- Interoperable with legacy banking infrastructure
- Easy document archival and audit trail generation
XML API in Healthcare: Enabling Interoperability
Healthcare systems are complex and fragmented. XML provides a reliable structure to bridge the gap between various platforms, ensuring smooth data exchange across:
Key Use Cases:
- HL7 and CDA Documents
HL7 v3 standards, Continuity of Care Documents (CCD), and Clinical Document Architecture (CDA) all use XML to store patient data. - Electronic Health Records (EHR)
XML APIs are used to sync patient data between hospitals, labs, insurance providers, and mobile apps. - Medical Devices & Systems Integration
Devices send structured patient readings (e.g., blood pressure, heart rate) via XML interfaces to central systems. - Insurance Claim Filing
Standardized XML formats used for insurance eligibility checks, claim submissions, and status tracking.
Benefits in Healthcare:
- Promotes interoperability between systems from different vendors
- Ensures semantic accuracy of health data
- Enables centralized access to patient records
- Supports compliance with HIPAA, GDPR, and other regulations
Challenges in XML API Integrations
Despite its strengths, XML APIs face several hurdles:
| Challenge | Explanation |
| Verbosity | XML is heavier and more verbose than JSON, affecting speed and payload size |
| Parsing Complexity | Requires dedicated parsers and validation processes |
| Slower Performance | More CPU-intensive parsing than lightweight JSON |
| Developer Adoption | Modern dev teams prefer REST+JSON due to its simplicity |
| Security Risks | Vulnerable to XML External Entity (XXE) attacks if not properly configured |
Best Practices for XML API Implementation
1. Use Well-Defined Schemas
- Always validate incoming and outgoing XML against XSD.
- Ensure structure and semantics are strictly enforced.
2. Secure Your XML Endpoints
- Sanitize inputs to prevent XXE or XML bomb attacks.
- Enforce HTTPS with TLS 1.2 or higher.
3. Compress Payloads
- Enable GZIP compression to reduce transfer time for large XML files.
4. Optimize Parsers
- Use libraries like libxml2, lxml, or SAX for efficient parsing.
- Use streaming parsers for large datasets.
5. Maintain Backward Compatibility
- Ensure new versions of your API do not break existing consumer integrations.
Future of XML APIs in Regulated Industries
While JSON and GraphQL APIs will continue to gain ground in most commercial applications, XML APIs aren’t going away anytime soon, especially in:
- Healthcare (due to HL7, FHIR XML, and device integrations)
- Finance (due to ISO 20022 mandates by SWIFT)
- Travel (as GDS systems evolve slowly)
Forward-thinking companies should adopt hybrid API strategies—using XML where compliance and legacy integration is essential, and JSON elsewhere for agility.
Conclusion
XML API integrations remain essential in industries where structure, validation, and interoperability matter the most. While modern formats offer convenience and speed, they often lack the rigor and robustness required in fields like travel, finance, and healthcare.
Organizations operating in these sectors must continue to support and modernize their XML APIs, ensuring they are secure, well-documented, and optimized for performance—while preparing for a future that may mix XML and JSON in strategic ways.
FAQs
1. What is the difference between XML and JSON in API integration?
XML is more verbose and structured with schema validation, while JSON is lighter, easier to read, and preferred in web and mobile development.
2. Why do industries like travel and healthcare still use XML APIs?
They rely on legacy systems, require standardized and validated data formats, and must comply with strict regulations—making XML a necessity.
3. Can I convert XML APIs to REST or JSON?
Yes, using middleware or adapters, XML can be translated into JSON to support modern frontends or mobile apps, but core systems may still rely on XML.
4. What is the future of XML APIs?
They will continue to thrive in regulated industries. Rather than being replaced, XML APIs are being modernized and integrated with REST/JSON layers for flexibility.
