Software Engineer, Agent Harness

sim· Engineering
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📍 San FranciscoFullTime💰 USD 210K–260K

About this role

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.

Frequently Asked Questions

What is the salary for the Software Engineer, Agent Harness role at sim?
The listed salary for this Software Engineer, Agent Harness position at sim is USD 210K–260K. This is an FullTime role.
Where is the Software Engineer, Agent Harness position at sim located?
This Software Engineer, Agent Harness role at sim is based in San Francisco. The position is listed as on-site or hybrid. Check the full job description or apply directly to confirm the work arrangement.
Is the Software Engineer, Agent Harness role at sim full-time or part-time?
This is listed as a FullTime position. It is posted as a Software Engineer, Agent Harness role in the Engineering department at sim.
Which team or department does the Software Engineer, Agent Harness at sim belong to?
This Software Engineer, Agent Harness position is part of the Engineering department at sim. See the full job description for more information about the team structure and responsibilities.
How do I apply for the Software Engineer, Agent Harness position at sim?
Click the "Apply Now" button on this page. You will be redirected to sim's official application portal hosted on ashby where you can submit your application directly.
When was the Software Engineer, Agent Harness job at sim posted?
This Software Engineer, Agent Harness position at sim was posted on Aug 26, 2026. Apply as soon as possible — early applications are often reviewed first.
Software Engineer, Agent Harness
sim · 💰 USD 210K–260K
Apply for this role ↗

You'll be redirected to sim's official application page on Ashby ATS.