Blitzy
Principal Software Engineer
$220K–$300K
Cambridge, MA · On-site · Principal · Full-time · Posted Sep 21, 2026
- Experience
- No number of years stated; requires prior Staff+, Principal Engineer, or comparable scope.
About the job
Own and ship critical production systems and high-impact backend features, including scalable infrastructure and production LLM systems, to improve customer outcomes and engineering velocity.
What you'll do
- Own mission-critical production systems end-to-end, including reliability, performance, scalability, and operations.
- Design, build, and ship backend systems, cloud infrastructure, and LLM-powered systems with evaluation and validation loops.
- Resolve technical bottlenecks and make durable technical decisions while modernizing enterprise systems.
What they ask for
- Direct experience using Python as a primary language, backend frameworks, and microservices architectures; expertise in REST and gRPC, with proficiency in Node.js and JavaScript.
- Proficiency in AWS and at least one additional cloud platform; advanced production knowledge of Kubernetes and Terraform.
- Experience operating highly available production systems and strong knowledge of SQL and NoSQL databases.
- Hands-on production experience with LLM systems and a proven record operating at Staff+, Principal Engineer, or comparable scope.
Nice to have
- Working knowledge of LangSmith or comparable LLM observability and evaluation tools.
- Familiarity with OpenAI, Anthropic, or similar model providers.
Pay
$220,000 - $300,000 USD base salary; bonus and equity also stated, with no amounts specified.
Tools
Python, REST, gRPC, Kubernetes, Terraform, AWS, LangSmith, OpenAI
AI focus
Build and operate production LLM-powered systems, including evaluation, validation, regression testing, tracing, and failure analysis; develop semantic retrieval systems using vector databases or embedding infrastructure.
Model-written summary · the original posting is authoritative