Principal Software Engineer

Principal Engineer (Backend / Platform)

About Blitzy

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

About Blitzy

Blitzy is a Cambridge, MA based AI software development platform on a mission to revolutionize 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.

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 or an architecture-only role. We are looking for someone who has operated at Principal / Staff scope in a highly technical environment and expects to spend their time writing, reviewing, and shipping production code. 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 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
• gRPC-based services (REST, gRPC)Node.js and JavaScript (supporting layers)

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 modeling 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 modernizing — complex, long-lived production environments

Ways to Stand Out

• Deep understanding of how enterprise software systems are built and evolved at scale, including tradeoffs 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 energizing community
• Unlimited snacks, fizzy water, coffee, espresso, and whatever else you need to perform at your best

Our Culture:

Who we are: Led by two pioneering co-founders we are one of the fastest growing companies in the U.S., creating our own category of enterprise autonomous software development. We automate thousands of hours of software development for our customers, which includes strong representation within the Fortune 500

How we work:

We move Blitzy Fast:

Time is both our company's and our clients' most precious asset. We move quickly and decisively to innovate internally and deliver exceptional software externally.

Championship Mindset:

We operate like a professional sports team. We win as a team by holding ourselves and each other to high standards, collaborating in-person, and remaining focused on the mission

Passion for Invention:

We're pushing the frontier of what's possible, requiring constant innovation and innovation

We Work for the Customer:

We focus on delivering outsized value to the customers we work with and expanding those relationships into deep, meaningful partnerships.

We believe in being 'everyday athletes'—taking care of ourselves so we can bring our best minds to work. We promote great sleep, movement, and restorative activities for optimal mental performance. It makes for a happier and more productive team.

Blitzy is an equal opportunity employer committed to building a diverse and inclusive team. We believe different perspectives make us stronger.