Staff SW Engineer

Fastino Labs is building specialized, efficient LLMs. The Staff Software Engineer will help define the platform’s technical direction, build agent and AI training and inference systems, deploy the platform, and partner with researchers and customers to bring models and features into production.

Responsibilities:

• Help define the technical direction for Fastino’s platform, contributing to the architecture decisions that let us scale without slowing down
• Design and build our agent harness, including the runtime loop, tool calling, context management, and error recovery, plus the eval harnesses that measure agent reliability
• Build and scale our AI training and inference pipelines, pushing on latency, throughput, and cost as usage grows
• Own deployment of the Fastino platform into customer-managed AWS VPCs using Kubernetes and Terraform, including install, upgrade, and observability paths that work in environments we don’t control
• Build secure sandboxed execution environments for agentic workloads on Modal Sandboxes
• Ship full-stack features end-to-end while owning the hardest, most ambiguous problems on the team
• Partner closely with AI researchers to take new models from research to production, including deployment, evaluation, and monitoring
• Raise the engineering bar through code reviews, mentorship, and setting practices the rest of the team builds on, including how we work with AI coding agents
• Talk to customers and turn their feedback into product decisions, fast