Principal Engineer (Backend / Platform)

About Blitzy

Blitzy is a Cambridge, MA based rapidly scaling Generative AI start-up.

The Blitzy platform enables thousands of AI Agents to ‘think’ and cooperate for hours to generate high-quality code at scale for enterprises. The platform specializes in working with large-scale enterprise codebases and executing large-scale changes. The platform builds everything AI can deliver in a precise manner — around 80% of any roadmap or large-scale feature addition — supplemented with a human engineering guide to complete the remaining 20% needed for production. We deliver 3x–5x engineering velocity improvements to our enterprise customers. With over 27 patents and counting, Blitzy is actively hiring senior technologists in Cambridge, MA who have a passion for building AI that leverages “System 2 Thinking” to solve problems at inference. The company is rapidly growing.

Compensation: This role is compensated at the top of the market for Principal Engineers.

Expected total compensation is in the range of $300K–$500K, with a mix of cash and equity that reflects the scope, ownership, and impact of the role.

Final packages are tailored to demonstrated Principal-level experience and production ownership.

Location: One Kendall Square, Cambridge MA 02139 (In-person role)

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 organization through example and judgment

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