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Polymath

Simulated worlds for end-to-end AI training

Software Engineer

ContractUpdated on 10/23/2026
No salary listed
Mid
San Francisco, CA, USA
Remote
Software EngineeringAI Application Engineering

About the job

Requirements
  • Have strong engineering fundamentals.
  • Enjoy building from first principles and solving open-ended technical problems.
  • Have high agency and a strong bias toward shipping.
  • Maintain a high quality bar and care about building robust systems.
Responsibilities
  • Build simulation environments, tasks, and verifiers that challenge frontier models.
  • Build diverse, high-fidelity environments that test agents in realistic settings.
  • Design complex tasks that require long-horizon reasoning and tool use.
  • Develop robust verifiers that reliably measure agent performance.
  • Improve infrastructure and tooling to run, debug, and improve environments.
  • Work closely with the research team to identify failure modes and turn them into new tasks and benchmarks.

About the company

Polymath AI Labs builds simulated worlds to train AI agents on real-world, long-horizon tasks. Its simulations combine running applications, real tools, and multi-step workflows to teach end-to-end software development and other complex tasks. A flagship product, Horizon-SWE, evaluates an agent’s ability to plan, code, test, and deploy inside a simulated software company. The goal is to create reliable, autonomous AI systems that can operate with minimal human supervision in real-world settings.

Company Size

1-10

Company Stage

Seed

Total Funding

$130K

Headquarters

San Francisco, California

Founded

2025

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Simplify's Take

What believers are saying

  • YC listed Polymath active on August 26, 2026, with six employees.
  • Polymath updated its site on September 4, 2026, naming Base10, Cervin, and YC.
  • Horizon-SWE launched February 6, 2026 and benchmarked frontier models credibly.

What critics are saying

  • No public revenue, customer logos, or contracts prove demand beyond frontier labs.
  • OpenAI, Anthropic, and Google can build internal simulators faster than a six-person startup.
  • If benchmark quality stalls, Polymath becomes a replaceable services vendor by 2027.

What makes Polymath unique

  • Horizon-SWE uses a containerized software company with 73 tools and live traffic.
  • It scores agents across feature correctness, DevOps, and engineering quality, not toy tasks.
  • YC Winter 2026 founders bring Hume, Plaid, AWS, Amazon, and Berkeley pedigrees.

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Benefits

  • Health Insurance
  • Dental Insurance
  • Vision Insurance
  • 401(k)
  • Unlimited Paid Time Off
  • Commuter Benefits
  • Gym Membership
  • Meal Benefits