Feeny
Sim

Software Engineer, Agent Harness at Sim (San Francisco, CA)

Sim· San Francisco, CA· $210k–$260k·

Role details

Salary
$210k–$260k
Work type
Onsite
Employment
Full-Time

Job description

Our mission is to automate knowledge work. The first step in our journey is to build the best tool for teams to build agents.

Sim is talent-dense. We're looking for special people who are mission-driven, passionate, and creative.

About the Role

The agent harness is Sim. It's the agent that builds workflows, tables, creates knowledge bases, and does everyday tasks. As a member of this team, you'll build the agent that builds everything else: how it plans, calls tools, uses memory, recovers from failure, and runs reliably at scale for 100,000+ builders.

You may be a fit if

  • You can think clearly about LLM behavior (tool calls, context, retries, evals) and you can turn that intuition into robust infrastructure.

Compensation

$210K–$260K base plus 0.2%–0.8% equity.

Applying

If there appears to be a fit, we'll reach out to schedule 1-2 short technicals. After, we'll schedule an onsite in our office, where you'll work on a small project, discuss ideas, and meet the team.

EQUAL OPPORTUNITY

Sim is committed to creating an inclusive environment for all employees. We celebrate diversity and are committed to creating an inclusive environment for all team members. We do not discriminate on the basis of race, religion, color, national origin, gender, sexual orientation, age, marital status, veteran status, or disability status.

Why work at Sim

  • Early-stage impact: Join a 7-person team where every employee shapes product, culture, and direction.
  • High growth trajectory: 866% headcount growth in one year, rapidly scaling user base, and fresh Series A funding.
  • Compensation & equity: Competitive base salaries ($120K–$220K) plus meaningful equity (0.20%–1.20% depending on role).
  • Location & culture: Based in San Francisco; likely in-office/hybrid given small team. Founders emphasize collaboration (“build agents together in real-time”).
  • Technical pedigree: Surrounded by engineers from Amazon, UC Berkeley, and prior YC startups; work on cutting-edge AI infrastructure.

Application questions