Staff Engineer

Staff / Principal Software EngineerAI Agent Infrastructure | San Francisco, CA | On-site 5 days/weekCompensation: $250,000–$400,000 base + equity
Shields Group Search is partnered with a rapidly growing, well-funded AI infrastructure company building the critical layer that allows AI agents to reliably interact with the tools people use to work: developer platforms, communications tools, CRMs, knowledge bases, productivity software, and more.
The company is building deeply technical infrastructure across secure authentication, agent tool execution, search and planning, triggers, sandboxed environments, workflow orchestration, and reliable runtimes. This is a high-ownership engineering environment with a small, unusually ambitious team, real customer traction, and the opportunity to help define the technical and cultural standard for the company’s next phase.
They are hiring two Staff / Principal-level individual contributors. This is not an engineering management role. They are looking for hands-on, exceptional engineers who want to remain close to the code, take ownership of difficult systems problems, ship quickly, and operate across product, infrastructure, and customer needs.
What you’ll doBuild and evolve the core primitives and APIs behind an AI-agent platform, including authentication, token lifecycle management, automatic refreshes, triggers, tool search, tool planning, orchestration, and sandbox management.Design and operate backend and distributed systems that enable reliable, secure execution across many third-party applications and workflows.Work across multiple code-execution runtimes and sandboxed environments, including serverless and isolated compute systems.Improve reliability and performance through tracing, CPU and heap profiling, database optimization, workflow optimization, and systems-level debugging.Take on complex technical problems spanning infrastructure, backend systems, product engineering, developer experience, and AI-native workflows.Work directly with product engineering teams and customers to win demanding workloads, learn quickly from real usage, and improve the product accordingly.Write thoughtful, articulate documentation that makes complex systems understandable for engineers, customers, and internal stakeholders.Help set the engineering bar as an early senior technical hire, both through your work and through the standards you bring to architecture, product decisions, code quality, speed, and craft.
What they are looking forThis team is not hiring based on a rigid checklist. They care most about exceptional engineers with clear evidence of high ownership, strong product and engineering judgment, depth when needed, and an instinct to build.
The ideal candidate is a deeply hands-on Staff or Principal-caliber IC who has built and operated meaningful software systems at a high-bar engineering organization, particularly within developer tools, fintech, AI, infrastructure, data platforms, productivity software, APIs, distributed systems, or technically ambitious product companies.
They are especially interested in engineers who have demonstrated a trajectory similar to:Owning or leading major technical initiatives while remaining deeply embedded in implementation.Building and scaling backend, platform, infrastructure, data, or developer-facing products.Working at high-caliber product and engineering organizations where quality, speed, and ownership matter.Taking responsibility for core systems rather than operating only within a narrowly defined scope.Moving comfortably between product decisions, architecture, infrastructure, customer problems, and hands-on execution.Core strengthsDeep experience building and scaling backend or distributed systems.Strong instincts for maintaining reliable systems while shipping quickly.Ability to keep multiple moving parts of a complex platform in mind at once.Comfort operating in Linux environments.Strong written communication skills and the ability to explain complicated technical ideas clearly.Good judgment, intellectual honesty, and the ability to build trust quickly.AI-native mindset: you have built with language models and ideally built products or infrastructure for language-model-powered systems.Ability to work across the stack and across functions. You may be solving a frontend problem one day, an infrastructure problem the next, and helping shape a product decision the day after.
Helpful, but not mandatoryExperience with TypeScript and/or Go.Experience with authentication, OAuth, API keys, token refresh, permissions, or lifecycle management.Experience with agent tooling, LLM application infrastructure, tool calling, MCP, sandboxing, workflow orchestration, or code execution environments.Contributions to meaningful open-source projects.A history of building companies, large side projects, developer tools, products, or unusual technical experiments.Evidence that people use things you have made.
What this company means by “Engineer”This is a team that uses a high bar for the word engineer.
They believe an exceptional engineer has all three of the following:High intrinsic drive and side projects- You build because you cannot help yourself. That might mean open source, weekend projects, weird experiments, products, tools, writing, or things you made simply because you wanted them to exist.Cross-functional flex- You can work across the whole stack and across functions. You are not limited by job boundaries. You can engage with frontend, backend, infrastructure, product, design, customer needs, and technical strategy when the work requires it.Depth when needed - You are not merely broad. When a problem demands it, you can go extremely deep, understand the real complexity, and emerge with a clear answer.
They are not looking for someone who simply writes tickets or optimizes for a conventional career path. They are looking for capital-E Engineers: people who care deeply about the craft, are capable of independent judgment, and want to do work that matters.