William Smith Group 1832 Limited is implementing Oracle NetSuite as its core ERP platform (go-live 1 November 2026), with Celigo as the integration layer, with Phase 1 covering core back-office functions, warehousing and distribution, and Phase 2 covering manufacturing functionality. The in-house development team - two Senior Developers and a further developer with growing NetSuite skills - delivers day-to-day platform development.
This role exists to add senior technical depth and specialist breadth to that team: owning the architecture of complex and cross-cutting work, leading on integrations, acting as design authority and technical reviewer, and accelerating the wider team’s capability through mentoring and code review. It is positioned as a senior individual contributor role, parallel to the IT Manager on the technical track, complementing rather than competing with the existing developers.
Key Responsibilities:
- Act as design authority for NetSuite customisation and integration: architectural decisions, technical standards, code review, design sign-off on non-trivial work.
- Lead the design and build of the most complex SuiteScript work (Map/Reduce at scale, performance-critical Suitelets and RESTlets, advanced workflow logic) and act as escalation point for the team on technical problems.
- Own the integration architecture end-to-end: flow design patterns, error handling and recovery, monitoring strategy, onboarding of new endpoints, retirement of legacy integrations when required.
- Establish and maintain platform engineering disciplines: SuiteCloud Development Framework, source control, sandbox and release management, deployment pipelines, governance limit monitoring.
- Mentor and upskill the existing development team through pairing, structured knowledge transfer, code review and technical coaching.
- Partner with the IT Manager on platform roadmap, technical debt management and Phase 2 (manufacturing) technical design.
- Engage directly with business stakeholders on the most complex requirements; translate to technical design and supporting documentation.
- Contribute to third-line support as escalation specialist for the most complex incidents.
Strongly preferred (tier 1)
- Substantial hands-on NetSuite SuiteScript development experience (4+ years, all major script types, demonstrable production track record).
- Deep working experience of Celigo integrator.io - flow architecture, error handling at scale, complex transformations.
- Demonstrable design and architectural responsibility on a NetSuite implementation or estate - not solely build-to-spec experience.
- Strong NetSuite data model fluency: saved searches, custom records, scripted vs. workflow trade-offs, governance and performance considerations.
- Experience operating as a senior individual contributor - code review, mentoring, technical decision-making.
Acceptable with development plan (tier 2 – alternative entry routes)
- Senior integration architect background on comparable platforms (Boomi, MuleSoft, Workato) with NetSuite exposure and willingness to specialise in Celigo.
- NetSuite SuiteCloud Developer II or Administrator certification.
- CPQ tooling experience.
- Manufacturing ERP functionality exposure (inventory, work orders, BOMs) - relevant to Phase 2.
- Git-based source control and CI/CD for NetSuite (Salto, Blue Yonder or equivalent tooling).
- SQL, Python or other scripting languages for tooling and data work.
- Manufacturing, distribution or food and beverage sector background.
- Experience with BI tooling (principally Phocas).
Personal Attributes
- Comfortable as senior technical voice without being the line manager - collaborative with both the IT Manager and the existing development team.
- Mentoring mindset; gets satisfaction from levelling up a team rather than hoarding the complex work.
- Pragmatic on engineering rigour - applies standards proportionately to the business context.
- Strong written and verbal communication with non-technical stakeholders.
- Committed to the agreed on-site working pattern
What the Role Offers
- Senior technical role on a newly implemented enterprise platform with a clear Phase 2 roadmap ahead.
- Genuine design authority and influence over the long-term technical direction.
- Strong existing team to work with and develop, not a green-field rebuild.
What we offer:
- Pension Scheme
- Life Assurance 6x Salary
- Free Parking
- Employee Assistance Programmes
- Training and career development
- Holiday Purchase Scheme
- Holiday Loyalty Reward Days
- Cycle to Work Scheme
- Tech scheme and Employee Discounts
Location: Barnard Castle, County Durham (hybrid – minimum 2 days on-site per week)
Job Type: Full-time, Permanent
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Principal NetSuite Developer in Barnard Castle employer: William Smith Group 1832
At William Smith Group 1832 Limited, we pride ourselves on fostering a collaborative and innovative work culture that empowers our employees to excel in their roles. As a Senior NetSuite Architect & Integration Lead, you will not only have the opportunity to shape the future of our ERP platform but also benefit from continuous professional development and mentorship within a supportive team environment. Located in a vibrant area, we offer a range of employee benefits that enhance work-life balance and promote personal growth, making us an exceptional employer for those seeking meaningful and rewarding careers.
