Tandem Developer

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

• Design, develop, and maintain applications on the HP NonStop (Tandem) platform

• Develop and support solutions using TACL, Cobol, C, and Guardian

• Deliver and enhance card transaction processing, authorization, and settlement systems

• Integrate with core banking platforms, payment gateways, and downstream systems

• Perform system analysis, troubleshooting, and performance tuning in high-volume environments

• Ensure compliance with PCI DSS, security, and regulatory standards

• Provide L2/L3 production support for critical card and banking applications

• Collaborate with business analysts, engineers, and stakeholders to deliver scalable solutions

Required Skills & Experience

• Strong hands-on experience with HP NonStop (Tandem) systems

• Proficiency in TACL, Cobol, C, Guardian, and Enscribe/NonStop SQL

• Solid understanding of ISO 8583 messaging and online/batch transaction processing

• Proven experience in the Cards domain (credit/debit card processing, EMV, tokenization)

• Experience with Base24 or similar card payment platforms

• Strong analytical, troubleshooting, and problem-solving skills

• Experience working with high-availability, fault-tolerant systems

Desirable Experience

• Modernisation or transformation of Legacy Tandem applications

• Exposure to Visa/Mastercard schemes, fraud prevention, and settlement processes

• Banking or payments-focused certifications or formal training