Principal NetSuite Developer

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.

Essential Criteria:

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)

• Deep Celigo integrator.io expertise, plus working NetSuite experience (administrator, junior developer or partner-side functional / technical) and strong JavaScript / TypeScript background.
• Senior integration architect background on comparable platforms (Boomi, MuleSoft, Workato) with NetSuite exposure and willingness to specialise in Celigo.
• Senior developer or architect on a comparable mid-market ERP (Dynamics 365 Business Central, Sage Intacct, Acumatica) with strong JavaScript / TypeScript skills and a credible NetSuite learning path.

Desirable

• 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

To apply please send your CV with a covering letter to [email protected]

Pay: From £50,000.00 per year

Benefits:

• Casual dress
• Company pension
• Cycle to work scheme
• Free parking
• On-site parking

Work authorisation:

• United Kingdom (required)
• Work Location: In person