Tandem Developer (Contract) – Cards & Banking
📍 Location:
London (2–3 days onsite)
📅 Contract Duration:
Until 31 December 2026
💼 Engagement:
PAYE via Umbrella only
🔐 Security:
BPSS eligibility required
Role Overview
We are seeking an experienced Tandem Developer to join a technology team delivering mission-critical banking and card payment solutions. This role focuses on the Cards domain, working within a high-availability environment supporting large-scale transaction processing systems.
You will be responsible for developing, enhancing, and supporting HP NonStop (Tandem) applications that underpin card authorization, settlement, and payment processing platforms.
Key Responsibilities
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Design, develop, and maintain applications on the HP NonStop (Tandem) platform
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Develop and support solutions using TACL, COBOL, C, and Guardian
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Deliver and enhance card transaction processing, authorization, and settlement systems
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Integrate with core banking platforms, payment gateways, and downstream systems
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Perform system analysis, troubleshooting, and performance tuning in high-volume environments
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Ensure compliance with PCI DSS, security, and regulatory standards
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Provide L2/L3 production support for critical card and banking applications
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Collaborate with business analysts, engineers, and stakeholders to deliver scalable solutions
Required Skills & Experience
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Strong hands-on experience with HP NonStop (Tandem) systems
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Proficiency in TACL, COBOL, C, Guardian, and Enscribe / NonStop SQL
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Solid understanding of ISO 8583 messaging and online/batch transaction processing
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Proven experience in the Cards domain(credit/debit card processing, EMV, tokenization)
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Experience with Base24 or similar card payment platforms
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Strong analytical, troubleshooting, and problem-solving skills
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Experience working with high-availability, fault-tolerant systems
Desirable Experience
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Modernisation or transformation of legacy Tandem applications
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Exposure to Visa/Mastercard schemes, fraud prevention, and settlement processes
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Banking or payments-focused certifications or formal training
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