Senior Site Reliability Engineer - Connex

Our Purpose

Mastercard powers economies and empowers people in 200+ countries and territories worldwide. Together with our customers, were helping build asustainableeconomy where everyone can prosper. We support a wide range of digital payments choices, making transactionssecure, 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 - ConnexAbout 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 UKs 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.
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The Opportunity
We are seeking a Site Reliability Engineer II to support mission-critical applications within the UKs 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.
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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
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Connex Domain Experience
Experience with Connex and related technologies in a live production environment is highly desirable, including:
HP NonStop systems
Pathway, GoldenGate, 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 ISO8583, VISA, Mastercard, LIS5
HSMs, cryptology and TLS
Source code management and controlled deployments
Full SDLC lifecycle experience (design, development, testing, implementation, support)
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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
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Skills & Experience
Strong communication, organisation, and time management skills
Proven ability to troubleshoot complex systems under pressure
Experience in financial services or payments environments
Understanding of ITIL practices, change, and release management
Familiarity with Agile methodologies and team-based delivery
Experience with functional and non-functional deployments
Knowledge of programming or web technologies is an advantage
Strong analytical mindset with a focus on continuous improvement and tooling
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Personal Attributes
Passion for production support, diagnostics, and reliability engineering
Proactive, self-driven, and committed to continuous learning
Collaborative team player with a flexible, adaptable mindset
Motivated to improve processes and embrace emerging technologies
Strong ownership mindset with a desire to make a meaningful impact

Corporate Security Responsibility

All activities involving access to Mastercard assets, information, and networks comes with an inherent risk to the organization and, therefore, it is expected that every person working for, or on behalf of, Mastercard is responsible for information security and must:

• Abide by Mastercards security policies and practices;

• Ensure the confidentiality and integrity of the information being accessed;

• Report any suspected information security violation or breach, and

• Complete all periodic mandatory security trainings in accordance with Mastercards guidelines.