Principal Backend Engineer, High-Impact AI Systems

Blitzy; Boston (MA); On-site; USD 180,000 - 260,000; Full time

Job summary

Blitzy seeks a Principal Engineer to own Blitzy's production-grade systems and deliver high-leverage features that boost customer outcomes and engineering velocity. This is the most senior individual contributor role at Blitzy today, focused on writing, reviewing, and shipping production code.

This 100% hands-on role emphasizes system ownership, execution quality, and durable technical decisions across backend, frontend, infrastructure, and AI systems, with no people-management duties.

Qualifications

• 12+ years of Python + backend/microservices experience.
• REST and gRPC expertise with Node.js/JavaScript.
• AWS proficiency with GCP or Azure.
• Kubernetes and Terraform in production.
• Experience with SQL/NoSQL databases (PostgreSQL, MySQL, MongoDB, Cassandra, DynamoDB).
• Familiarity with graph databases (Neo4j) and vector databases.
• Hands-on experience with LLM-powered systems in production.
• LangSmith or similar observability tools, model-provider familiarity.
• Full-stack capability across frontend, backend, infra, and AI.

Responsibilities

• 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 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.

Skills

Python

REST

gRPC

Node.js

JavaScript

AWS

GCP

Azure

Kubernetes

Terraform

SQL

NoSQL

PostgreSQL

MySQL

MongoDB

Cassandra

DynamoDB

Neo4j

Vector DBs

LLM systems

LangSmith

Tools

LangSmith

Job description

Blitzy seeks a Principal Engineer to own Blitzy's production-grade systems and deliver high-leverage features that boost customer outcomes and engineering velocity. This is the most senior individual contributor role at Blitzy today, focused on writing, reviewing, and shipping production code.

This 100% hands-on role emphasizes system ownership, execution quality, and durable technical decisions across backend, frontend, infrastructure, and AI systems, with no people-management duties.