Senior ServiceNow Developer

The Senior ServiceNow Developer is the most senior hands-on technical authority for the ServiceNow platform underpinning our cybersecurity managed services. The role designs, builds and maintains complex, heavily customised applications in an environment where out-of-the-box functionality is not sufficient: scoped applications, custom data models, advanced server- and client-side scripting, and integrations with security tooling and customer environments. It demands expert-level JavaScript, a rigorous approach to performance, maintainability and upgradeability, and the judgement to know when to configure, when to customise, and when to challenge the requirement. Because the platform delivers a live managed service to external customers, the post holder works directly with customers and service stakeholders on requirements, technical escalations and service impact, and is accountable for solutions that hold up under contractual service commitments. As the technical lead within the development team, the post holder sets the technical standard, owns code review and architectural direction, and mentors and develops the wider team.

Key Responsibilities

• Technical Leadership: Act as the technical authority for the platform: own architectural direction and technical standards, make and document the significant design decisions, and provide the final technical sign-off before code is promoted.
• Complex Application Development: Design and build scoped applications, custom data models and business logic that go well beyond out-of-the-box capability, while keeping the instance supportable and upgradeable.
• Advanced Scripting and JavaScript Engineering: Write, review and refactor advanced server-side and client-side JavaScript across Script Includes, Business Rules, GlideAjax, Scripted REST APIs, UI Scripts, UI Actions and Service Portal widgets, applying sound engineering practice within the constraints of the platform.
• Customer-Facing Solution Design: Work directly with customers and service stakeholders to shape requirements into technical designs, explain trade-offs and constraints in plain language, and ensure what is delivered is operable within the managed service and its contractual commitments.
• Integrations: Design and build robust integrations with external systems, security tooling and customer platforms using REST and SOAP, including authentication, error handling, retry behaviour and monitoring.
• Platform Health and Upgradeability: Own the technical quality of a heavily customized, multi-customer set of instances: performance tuning, reduction of technical debt, upgrade impact analysis and remediation of skipped or broken customisations.
• Code Review and Technical Standards: Set and enforce coding standards, secure development practice and peer review across the team, and drive consistent, measurable improvement in code quality.
• Complex Troubleshooting and Escalation: Act as the final escalation point for the most complex defects and customer-impacting production issues, including root cause analysis across integrations, ACLs, asynchronous processing and performance, and communicate findings to service and customer stakeholders.
• Mentoring and Capability Building: Coach developers and administrators through pairing, design reviews and technical walkthroughs; grow the technical depth of the team and reduce single points of knowledge.
• Documentation: Produce and maintain technical documentation, integration specifications and runbooks to a standard that allows others to support and extend the work.
• Collaboration: Work closely with ServiceNow administrators, frontend developers, UX and service delivery colleagues to ensure solutions are implemented and operated seamlessly end to end.

Skills, Knowledge & Expertise

• Hands-on ServiceNow development experience, including a minimum of 3 years in complex, heavily customised, multi-application enterprise instances rather than out-of-the-box implementations
• Expert-level JavaScript: strong command of server-side scripting within the platform's runtime as well as modern client-side JavaScript, including debugging, refactoring and performance-conscious code
• Demonstrable experience as the most senior technical developer on a platform or team: setting standards, owning code review, making architectural decisions and mentoring other developers
• Experience delivering ServiceNow within a managed service, MSP or multi-customer environment, including direct engagement with customers on requirements, technical escalations and service impact
• ServiceNow Certified Application Developer (CAD) and Certified System Administrator (CSA)
• Expert knowledge of platform development: scoped applications, data model and table design, Business Rules, Script Includes, GlideRecord and GlideAggregate, ACLs, Flow Designer, scheduled jobs and asynchronous processing
• Deep knowledge of ServiceNow client and server APIs, including Scripted REST APIs, GlideAjax and the differences between scoped and global application development
• Proven experience designing and maintaining integrations (REST, SOAP, OAuth and SSO patterns) with external and customer-side systems
• Demonstrable experience of performance tuning, advanced debugging and diagnosing complex platform issues in production
• Experience of platform upgrades on a customised instance, including impact analysis and remediation
• Secure software development lifecycle (SSDLC) practice, structured release management and version control (update sets, application repositories, ATF, CI/CD)
• Ability to work autonomously, own delivery end to end, and set technical direction for others
• Excellent written and verbal communication in English, including the ability to explain technical trade-offs and service impact to non-technical and customer stakeholders

Desirable Requirements

• Bachelor's degree in computer science, information systems or a related field
• Additional ServiceNow certifications (CIS in relevant modules, Certified Technical Architect or Certified Master Architect)
• Experience with modern frontend frameworks, in particular React
• Experience in a cybersecurity or managed services environment (Security Operations, Vulnerability Response, SIEM, SOC)
• Experience working in an agile delivery model with Jira and Azure DevOps
• Line management or formal technical lead experience

Job Benefits

• Flexible Working : Balance your work and personal life with our flexible working options.
• Generous Holiday Allowance : Enjoy 25 days of holiday, plus bank holidays, with the option to buy up to 5 additional days of annual leave.
• Medicash & Critical Illness Scheme
• Financial & Investment Benefits: Enjoy peace of mind with our Pension, Life Assurance, and Share Save Scheme.
• Community & Volunteering Programmes: Make a difference in your community with our volunteering opportunities.
• Green Car Scheme: Drive green and save money with our eco-friendly car scheme.
• Cycle Schem e: Stay fit and healthy with our cycle-to-work scheme.
• Special Time Off : Take time off for those big moments in life, like getting married/entering into a civil partnership, becoming a grandparent, and welcoming home a new pet.
• Family Planning : Benefit from our generous maternity and paternity leave, as well as time off and support for those undergoing fertility treatments.