Principal Software Engineer - AI Architecture

About the role

Checkbox is a Series A, Sequoia-backed start-up building an AI-first platform for in-house legal teams, now expanding into AI-powered intake, matter management, triage and work orchestration. It is looking for a hands-on Principal Engineer to act as the senior technical authority across its product engineering streams, especially around building and implementing its emerging AI architecture. The role reports to the VP of Engineering and is a technical leadership position, not a people-management one.

Key responsibilities

• Own key architecture decisions across product engineering streams, including high-consequence one-way-door decisions
• Define, document and govern the future-state product architecture, keeping it coherent across Product, Platform, Data Engineering, QA, Enterprise IT and other teams
• Design and help build initiatives that let engineering teams ship higher-quality software faster
• Contribute directly to production releases and drive engineering decisions through data, feedback loops and measurable quality signals
• Embed fitness functions, architecture measures and technical feedback loops into product engineering
• Partner with Data Engineering on the data and AI reference architecture, and ensure tenancy, security and compliance are designed in from the start
• Work with Product, Customer Success and Sales so architecture reflects real customer and commercial needs

Required profile

• Significant experience as a Principal Engineer, Staff Engineer, Architect or senior technical leader in a modern SaaS environment
• Proven track record of making and governing high-impact architecture decisions across multiple teams
• Comfortable contributing to production systems while setting broader technical direction
• Strong product and customer judgement, able to connect technical decisions to commercial outcomes
• Excellent communication skills and ability to influence through credibility and working code
• Pragmatic, hands-on and comfortable in a fast-moving scale-up environment

Required skills

• Deep systems expertise across product engineering, platform architecture, distributed systems and modern cloud-native software
• Understanding of tenancy, security, compliance and data isolation in enterprise SaaS
• Experience working closely with platform, data, QA, infrastructure or enterprise IT teams

What we offer

• Competitive salary and hybrid working with team days in the Sydney CBD office
• Personal learning and development budget and flexible leave policy
• Expense policy and salary sacrifice options
• Start-up hub with snacks, drinks, premium coffee and team socials, plus company-wide events and annual off-sites