Backend Engineer (Platform)

Sunollo is building a premium residential energy platform that combines high-quality hardware, reliable installation operations, and software to make clean energy simple for homes in Singapore.

We are looking for a Backend Engineer (Platform) to design, build, and own revenue-critical backend systems. The initial focus of this role is to build the foundation of our billing platform, followed by broader platform and internal systems.

This role is suitable for a senior backend engineer who enjoys high ownership, clear scope, and building production systems that are reliable and maintainable.

Key Responsibilities

• Design and implement backend systems that are revenue-critical and operationally important

• Build a billing and invoicing engine supporting subscriptions and milestone-based payments

• Design clean, auditable data models and event logs with replay safety

• Integrate with third-party systems such as Xero using OAuth2, APIs, and webhooks

• Implement secure and reliable background jobs and workflows (subscriptions, reminders, billing milestones)

• Ensure system reliability through logging, monitoring, alerting, and failure recovery mechanisms

• Build backend APIs to support internal admin tools and customer-facing applications

• Collaborate closely with product, finance, and operations teams to deliver correct system behaviour

• Write well-tested, maintainable code for critical system paths
  
  Job Requirements

  Must Have

  • Strong backend engineering fundamentals with experience shipping production systems

  • Experience with PostgreSQL and practical database design

  • Experience building and operating API integrations (OAuth2, webhooks, retries, idempotency)

  • Strong understanding of system reliability, monitoring, and failure handling

  • Ability to work independently with high ownership and minimal supervision

  Good to Have

  • Experience with billing systems, subscriptions, invoicing, or payments

  • Experience integrating accounting or CRM systems (e.g. Xero, HubSpot, Salesforce)

  • Experience with Supabase or managed Postgres / serverless environments

  • Experience building internal tools or admin dashboards

  • Startup or fast-growth company experience

    Qualifications

    • Degree in Computer Science, Engineering, or related field (or equivalent practical experience)

    • Senior level preferred (5+ years of backend engineering experience) strong mid-level candidates may be considered