Senior Software Engineer - Connex

Salary: £60,000 - 100,000 per year

Requirements:

• Extensive Connex development experience on HP NonStop.
• Understanding of financial-industry hardware, including ATMs, HSMs, and HP NonStop, and related standards and security requirements, including PCI and OWASP.
• Strong understanding of online transaction processing, including ATM transaction processing.
• Experience with TCP/IP and communication protocols.
• Strong knowledge of TAL, COBOL, SCOBOL, and TACL.
• Understanding of EMV and chip-and-PIN technology.
• Knowledge of HP NonStop protocols, security, and utilities.
• Strong understanding of financial-industry protocols, including ISO 8583, ISO 20022, LIS5, Visa, Mastercard, and ATM message protocols.
• Knowledge of some of the following: GoldenGate, electronic file transfers, Java, UNIX, Spring, Hibernate, and XML.
• Proven development experience and a solid developer background across multiple platforms.
• Proven technical testing experience in Agile environments, particularly with BDD methodologies.
• Hands-on automation testing expertise using open-source technologies such as Selenium, Cucumber, Gherkin, and Spring.
• Comfort with regular stakeholder demonstrations and pair programming.
• Excellent communication skills and ability to collaborate effectively in a multidisciplinary team.
• Excellent time-management and organisational abilities.
• Strong problem-solving skills and a proactive attitude.
• Passion for testing, development, and technology design across diverse full-stack platforms.
• Demonstrated experience in functional and non-functional automated testing.
• For work involving access to our assets, information, and networks: follow our security policies and practices, protect the confidentiality and integrity of accessed information, report suspected security violations or breaches, and complete mandatory periodic security training in accordance with our guidelines.

Responsibilities:

• Participate in prioritisation discussions with Product and Business stakeholders, and estimate and own delivery tasks—including design, development, testing, deployment, configuration, and documentation—to meet business requirements.
• Automate software build, operation, and execution activities for development and testing.
• Lead discussions about code, design, and process trade-offs as needed.
• Report status and manage risks for the primary application or service.
• Integrate services with a focus on the customer journey and experience.
• Demonstrate work and conduct acceptance discussions with Product Owners; understand and improve operational and engineering experiences and metrics in the area of ownership.
• Develop an end-to-end understanding of technical architecture and dependent systems.
• Promote technology standards and frameworks, and review team members coding, testing, and automation work.
• Mentor and guide newer team members, identify process improvements, and eliminate waste.
• Share and seek knowledge across the Guild or Programme to promote reuse of patterns, libraries, and practices.
• Contribute to project test strategies, including BDD-style functional, system-integration, and non-functional testing for volume, performance, resilience, and availability.
• Design test scenarios that uncover less obvious potential issues.
• Lead online real-time transaction-switching and ATM-acquiring testing across multiple platforms.
• Set up, maintain, and execute test-automation frameworks across application platforms.
• Identify automation opportunities and prioritise efforts based on risk throughout the delivery lifecycle.
• Establish and demonstrate traceability from business requirements to acceptance criteria from project inception.
• Advance automation across application tiers, including UI, APIs, CLIs, Connex, HP NonStop, and database layers.
• Investigate and resolve technical issues reported by customer support.
• Build comprehensive test scenarios and acceptance tests while collaborating in an iterative deployment environment.

Technologies:

• COBOL
• Cucumber
• Hardware
• Hibernate
• Support
• Java
• LESS
• OWASP
• Security
• Selenium
• Spring
• TCP/IP
• Unix
• XML
• UX UI Design
• HSM

More:

We are Mastercard, a technology leader in global payments. We connect consumers, financial institutions, merchants, governments, and businesses worldwide, supporting secure and convenient electronic transactions in more than 200 countries and territories. Our technology, innovation, partnerships, and networks support digital payments and help build a sustainable economy. Our Vocalink technologies underpin the UKs real-time payments, settlements, and ATM networks. We are seeking a Senior Connex Software Development Engineer for a dynamic, cross-functional team working within the SAFe methodology. This full-time engineering role offers an opportunity to contribute to the advancement of payment technologies and make a difference in the payments industry. Job number: R-274939; posted 2026-07-13.

last updated 40 week of 2026