Principal Backend Engineer

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 enterprise grade 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.

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 iteration.

• 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 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.

• Own mission-critical production systems end-to-end, ensuring correctness, scalability, performance, reliability, and operational excellence.

• Design, build, and ship high-impact backend systems and features that improve product reliability, performance, and customer value.

• Architect scalable services and cloud infrastructure using technologies such as Python, REST, gRPC, Kubernetes, and Terraform.

• Identify and resolve complex technical bottlenecks that limit engineering quality, system performance, or organizational velocity.

• Build and operate LLM-powered systems and validation loops that evaluate correctness, consistency, durability, and production performance.

• Design and evolve data architectures incorporating relational, NoSQL, graph, and vector databases to support complex enterprise applications and semantic retrieval.

• Modernize and improve complex enterprise systems while balancing reliability, maintainability, scalability, and delivery speed.

• Set and uphold engineering quality standards through hands-on technical leadership, sound technical judgment, and ownership of long-term technical decisions.

• 12+ years of direct experience with Python as a primary programming language, backend frameworks, and microservices architectures.

• Expertise in REST and gRPC, with proficiency in Node.js and JavaScript.

• Proficiency in AWS, along with experience using at least one additional cloud platform such as GCP or Azure.

• Advanced knowledge of Kubernetes and Terraform in production environments.

• Experience operating highly available production systems, including monitoring, scalability, reliability, performance optimization, and operational tooling.

• Strong knowledge of SQL and NoSQL databases, including PostgreSQL, MySQL, MongoDB, Cassandra, or DynamoDB.

• Familiarity with graph databases such as Neo4j and vector databases or embedding infrastructure for semantic search and retrieval.

• Hands-on experience building and operating LLM-powered systems in production, including evaluation, validation, regression testing, tracing, and failure analysis.

• Working knowledge of LangSmith or comparable LLM observability and evaluation tools; familiarity with OpenAI, Anthropic, or similar model providers is a plus.

• Ability to contribute across the full stack, with a strong understanding of frontend architecture and the ability to debug, design, and ship across frontend, backend, infrastructure, and AI systems.

• Understanding of large-scale enterprise software systems, including architecture, integration, deployment, modernization, and long-term maintainability.

• Proven track record of operating at Staff+, Principal Engineer, or comparable scope, independently driving complex technical initiatives and delivering high-impact outcomes with minimal supervision.

Blitzy is an equal opportunity employer committed to building a diverse and inclusive team. We believe different perspectives make us stronger. Base salary ranges are determined by country, role, level, experience, and skills. The range displayed on each job posting reflects Blitzy’s good faith determination of the minimum and maximum targets for new hire salaries across all locations. Individual pay is determined by related factors, including job skills, experience, and relevant education or training, which may impact a final offer. Your Talent Partner can share more about the specific salary range during the hiring process