Senior Site Reliability Engineer - Connex

Our Purpose

Mastercard powers economies and empowers people in 200+ countries and territories worldwide. Together with our customers, we’re helping build a sustainable economy where everyone can prosper. We support a wide range of digital payments choices, making transactions secure, simple, smart and accessible. Our technology and innovation, partnerships and networks combine to deliver a unique set of products and services that help people, businesses and governments realize their greatest potential.

Title and Summary

Senior Site Reliability Engineer - Connex About Mastercard
Mastercard is a global technology company in the payments industry, dedicated to enabling an inclusive digital economy that benefits everyone, everywhere. By making transactions safe, simple, smart, and accessible, we empower individuals, financial institutions, governments, and businesses to reach their full potential.
Our culture is driven by our Decency Quotient (DQ), which shapes how we work both internally and externally. Operating across more than 210 countries and territories, we are committed to building a sustainable world that unlocks priceless possibilities for all.
About Vocalink (a Mastercard Company)
Vocalink powers the UK’s critical payment infrastructure, including real-time payments, settlement systems, direct debits, and a nationwide ATM network of nearly 60,000 machines. Our systems process:

• Over 90% of UK salaries

• More than 70% of household bills

• Almost all state benefit payments
Joining Vocalink means contributing to systems that millions rely on daily.
The Opportunity
We are seeking a Site Reliability Engineer II to support mission-critical applications within the UK’s national payment infrastructure (FPS and CTS). This role is ideal for someone who thrives in a collaborative, agile environment and is passionate about reliability, continuous improvement, and modern technology.

Key Responsibilities

• Provide second-line support for mission-critical applications, ensuring adherence to service priorities and operational standards

• Support live production environments, including participation in a 24/7 on-call rota

• Deliver hotfixes, tooling improvements, and system housekeeping

• Work within a cross-functional Scrum team, contributing to application design, delivery, and technical consultancy

• Manage and implement changes, releases, and fixes in line with governance processes

• Support and maintain Disaster Recovery (DR) capabilities, including testing, risk management, and alignment with corporate strategy

• Collaborate with third-party suppliers for issue resolution and escalation to third-line support

• Ensure traceability from business requirements through to acceptance criteria

• Work closely with Service Management to resolve incidents, define enhancements, and improve system performance

• Maintain accurate and up-to-date technical documentation and artefacts
Connex Domain Experience

Experience with Connex and related technologies in a live production environment is highly desirable, including:

• HP Non Stop systems

• Pathway, Golden Gate, and electronic file transfer tools

• TACL, TAL, COBOL, SQL (Enscribe), Enform

• TACL scripting

• ATM switching, transaction processing, and financial networks

• Card authentication, authorization, and EMV standards

• Protocols and standards such as ISO
8583, VISA, Mastercard, LIS5

• HSMs, cryptology and TLS

• Source code management and controlled deployments

• Full SDLC lifecycle experience (design, development, testing, implementation, support)
Additional Responsibilities

• Drive innovation in production support, identifying opportunities to improve efficiency through automation and tooling

• Contribute to the production support strategy and roadmap, including technology selection

• Collaborate with stakeholders to design and implement effective solutions

• Participate in iterative, agile deployments as part of a Scrum team using Safe Agile

• Investigate production issues and perform root cause analysis
Skills & Experience

• Strong communication, organisation, and time management skills

• Proven ability to troubleshoot complex systems under pressure

• Experience in financial services or…