Founding Engineer - Platform & Infrastructure

About Litmus

Enterprises are rapidly deploying agents to automate complex work, and every one of them needs a reliable way to simulate, verify, and optimize those agents before trusting them with real work. Litmus gives them that confidence. We learn how a company's people actually work, generate the sandboxes, tasks, and verifiers to match, and evaluate its agents before they ship and once they're in production. The goal is an autonomous research engine that gives every enterprise the kind of internal benchmarking function the frontier labs have.

Litmus was founded by Sidharth Srinivasan, who led AI evals at Box after its CEO recruited him out of Stanford CS. He built the function from inception, running a research engineering team and owning Box's relationships with the frontier labs and data vendors. Litmus has raised $5M from Pear, BoxGroup, Workbench, and Emergence, alongside angels including Aaron Levie (CEO of Box), Arash Ferdowsi (co-founder of Dropbox), and senior leaders at OpenAI, Anthropic, Google, and Mercor. Demand already spans Fortune 15 enterprises, top US banks, AI transformation firms, and AI-native services companies, and we're hiring to keep up.

How we work: in person in FiDi, five days a week. Small team, high ownership, and we care about outcomes, not hours.

The role

Build the runtime that simulates the real world for AI agents.

Every Litmus evaluation runs inside a simulated copy of a company: its tools, its data, and its users. Thousands of agents run against those worlds in parallel, each run isolated, stateful, and replayable, often inside the customer's own cloud. Nothing off the shelf does this. You'll design it and own the architecture from day one.

What you'll work on:

• Stateful sandboxes that spin up, reset, fork, and replay on demand, at tens of thousands of runs

• Orchestrating large fleets of agents, fast and cheap

• Deploying into the most demanding enterprise environments: customer clouds, redaction, multi-tenancy, and security review

• Pulling production traces from the tools customers already use and turning them into tests

• The core architecture, and turning it into a product teams adopt on their own

Why it's exciting:

• Infrastructure is the moat here, not a dashboard on top of a database.

• What you build decides which customers we can say yes to, including some of the largest enterprises in the world.

• The runtime for agent simulation is still being invented, and the same environments that test agents today will train them tomorrow.

You might be a fit if

• You're a strong backend or infrastructure engineer who has been early before

• You've built and run production systems, and you're excited to own the parts you haven't done yet

• You're AI-pilled: you build with LLMs, work alongside coding agents every day, and have opinions about where agents break

• You make strong architectural calls with incomplete information

• You typically have 3–10 years of experience

Nice to have

• Cloud infrastructure across AWS, GCP, or Azure

• Containers, sandboxing, and isolation

• Distributed systems, workflow orchestration, and data pipelines

• Enterprise security and compliance

Probably not a fit

• Front-end only

• Roles where you never made the architectural calls

• Careers spent entirely inside very large companies

What we offer

• Founding equity and competitive cash

• One of the first hires, working directly with the founder and customers from day one

• Ownership of the platform architecture from the start

• A beautiful office in FiDi

• Breakfast, lunch, and dinner

• Medical, dental, and vision coverage

• Equinox membership or a fitness stipend

• Essentially unlimited budget for AI tools and tokens

• Relocation support if you're moving to San Francisco