Principal Software Engineer

About Blitzy

Blitzy is a Cambridge, MA based AI software development platform on a mission to revolutionise the software development life cycle by autonomously building custom software to unlock the next industrial revolution. We're transforming how enterprises build software, turning enterprise requirements into production-ready code with an agentic software development platform that can autonomously execute 80% of the quantum of software development work. We're backed by multiple tier 1 investors and have proven success as founders of previous start-ups.

The Role

We are hiring a Principal Engineer to take full, hands-on ownership of Blitzy's most critical production-grade systems and to deliver high-leverage features that materially improve customer outcomes and engineering velocity. This is the most senior individual contributor role at the company today. This is not a Senior-plus role, an architecture-only role, or a promotion-track role. We are looking for someone who has already operated at Principal / Staff+ scope in a highly technical environment and expects to spend their time writing, reviewing, and shipping production code. This role is 100% hands-on. Leverage comes from system ownership, execution quality, and durable technical decisions — not people management or process.

What Success Looks Like

• You independently own mission-critical production systems end-to-end.
• You ship high-leverage features that materially improve reliability, performance, and customer value.
• You raise the technical bar through working code and outcomes, not reviews alone.
• You identify and resolve the hardest technical bottlenecks limiting quality or velocity.
• You make technical decisions with long-term impact and stand behind them in production.
• You are a self-directed learner requiring minimal supervision.
• You are dedicated to getting things done right without making technical compromises.
• You demonstrate strong technical expertise across the full stack: frontend, backend, infrastructure, and AI systems.
• You materially increase the effectiveness of the engineering organisation through example and judgement.

Areas of Ownership

• End-to-end ownership of production-grade backend systems used by enterprise customers.
• Correctness, scalability, performance, and operational reliability in real environments.
• Delivery and stewardship of high-impact features, not just incremental improvements.
• Building and improving Blitzy using Blitzy, holding the platform to real-world standards.
• Designing, operating, and evolving LLM validation loops to ensure correctness, consistency, and durability in production.
• Setting engineering quality and durability expectations across teams without direct reports.

Core Technologies & Required Experience

This role demands strong, hands-on experience across the full technology stack. You should have deep expertise in most of the following:

• Backend: Python (primary language), Backend frameworks and microservices architectures, RPC-based services (REST, gRPC), Node.js and JavaScript (supporting languages).
• Cloud & Infrastructure: Expertise across at least two of AWS, GCP, and Azure, with GCP mandatory; Expert-level Kubernetes experience for container orchestration in production environments; Terraform for infrastructure as code; Production systems: monitoring, reliability, scalability, and operational tooling.
• Databases & Data Systems: Strong expertise across both SQL and NoSQL databases; SQL: PostgreSQL, MySQL, or similar relational databases; NoSQL: MongoDB, Cassandra, DynamoDB, or similar; Graph databases (Neo4j) for modelling and searching complex relationships; Vector databases/embeddings infrastructure for semantic search and retrieval.
• AI / LLM Tooling: Experience building and operating LLM-powered systems in production; Designing and implementing LLM validation loops (evaluation, feedback, regression testing, and failure analysis); LangSmith (or equivalent tooling) for tracing, evaluation, and debugging; Familiarity with specific models or vendors (e.g., OpenAI, Anthropic) is a plus.
• Frontend & Full-Stack Competency: Strong understanding of frontend frameworks and architecture; Ability to evaluate and contribute to frontend technical decisions; Demonstrated technical expertise across the full stack — you can debug, design, and ship across frontend, backend, infrastructure, and AI layers.
• Enterprise Systems: Core understanding of how large-scale enterprise systems are designed, integrated, deployed, and operated; Experience working within — or modernising — complex, long-lived production environments.

Ways to Stand Out

• Prior experience operating at Principal Engineer / Staff+ scope at a highly technical company.
• Deep understanding of how enterprise software systems are built and evolved at scale, including trade-offs around reliability, change management, and long-term maintainability.
• Clear ownership of complex systems that you designed, built, and supported in production.
• Hands-on ownership of LLM validation loops used to ensure correctness and durability in real environments.
• Experience designing systems that combine graph, vector, and traditional data models to support reasoning over complex domains.
• Proven ability to deliver outsized impact through the right features, not just more code.
• Track record of being a self-learner who requires minimal supervision and gets things done without compromising on quality.

Compensation

Total compensation: $300,000 - $500,000. This includes a mix of competitive base salary and equity, tailored to demonstrated Principal-level experience, scope of ownership, and production impact.

You'll Get…

• Competitive salary and equity.
• Paid medical, dental, and vision insurance for you and your dependents.
• 4% 401(k) match.
• Flexible vacation days, sick days, and work-from-home days.
• Technology (hardware, software, reading materials, etc.) equipment and/or allowance.
• The opportunity to re-shape an entire industry and create a platform that changes the future of software creation.
• A beautiful office environment with adjacent offices shared by other startups — an energising community.
• Unlimited snacks, fizzy water, coffee, espresso, and whatever else you need to perform at your best.