Software Engineer, Agents
<h2>About Sim</h2>
<p>Sim is the open-source platform to build, deploy, and orchestrate AI agents. Over 70,000 developers — from early-stage startups to the U.S. Department of Defense — use Sim to turn ideas into production-grade agentic workflows on a visual, Figma-like canvas. We connect to 1,000+ apps and LLMs, and our Copilot is the state of the art for building workflows with natural language.</p>
<p>We're a team of 5, YC X25, and backed by a $7M Series A led by Standard Capital with participation from Paul Graham, Perplexity, SV Angel, and Y Combinator. We're based in San Francisco and build in-person every day.</p>
<p>Our mission is simple: agents will run the world, and Sim is the primary means by which that happens.</p>
<h2>About the Role</h2>
<p>You'll own end-to-end development of our core agentic workflow engine and Copilot — the AI assistant that helps developers build and debug workflows using natural language, turning high-level intent into executable, reliable agents. This spans our backend (Next.js), orchestration layer, and all integrations with LLMs and external APIs.</p>
<p>Copilot is currently the best-in-class tool for building workflows with natural language. Your job is to keep it there and push it further — making it faster, more reliable, and capable of handling increasingly complex agentic architectures.</p>
<p>This is a foundational role. You'll set architecture decisions, reliability standards, and coding patterns that define how the core product works. On a team of 5, your work ships to tens of thousands of developers on fast release cycles.</p>
<h2>What You'll Do</h2>
<ul>
<li>Own the agentic workflow engine: the runtime that executes multi-step, tool-using agent workflows in production</li>
<li>Build and evolve Copilot — our natural language interface for creating, editing, and debugging workflows</li>
<li>Design and maintain integrations with LLM providers (OpenAI, Anthropic, Google, local models via Ollama) and external APIs</li>
<li>Architect the orchestration layer that turns visual flows into reliable, observable agent executions</li>
<li>Set technical standards for the codebase — reliability, testing, code quality, and architecture patterns</li>
<li>Work across the stack in our Next.js monorepo, shipping to production daily</li>
<li>Debug hard problems at the intersection of LLMs, distributed systems, and developer tooling</li>
</ul>
<h2>What We're Looking For</h2>
<ul>
<li>Strong generalist engineer who has shipped complex distributed systems or developer tools to production</li>
<li>Deep experience with TypeScript/JavaScript and Bun; comfort working in a Next.js monorepo</li>
<li>Track record of owning and operating production systems — you've been paged, you've debugged the weird ones, you've made things reliable</li>
<li>Experience integrating with LLMs or building on top of foundation model APIs</li>
<li>High agency and ownership — on a team this small, you define the roadmap as much as you execute it</li>
<li>Strong opinions on architecture, loosely held — you care about building things right but move fast</li>
<li>Experience with AWS infrastructure is a plus</li>
<li>Contributions to open-source projects are a plus</li>
</ul>
<h2>Why Sim</h2>
<ul>
<li>
<strong>Foundational impact.</strong> You're not joining a team — you're building one. Every decision you make shapes the product and the company.</li>
<li>
<strong>Real users, real scale.</strong> 70,000+ developers use Sim today. Your work ships fast and matters immediately.</li>
<li>
<strong>World-class backers.</strong> Series A - Standard Capital, Paul Graham, Perplexity, SV Angel, and Y Combinator believe in what we're building.</li>
<li>
<strong>Open source at the core.</strong> We've been open source from day one and we're proud of it. 26,000+ GitHub stars and growing.</li>
<li>
<strong>Competitive salary + meaningful equity.</strong> Early team, significant ownership.</li>
<li>
<strong>Full benefits.</strong> Comprehensive health insurance, relocation.</li>
<li><strong>Visa sponsorship available.</strong></li>
</ul>
<p>Sim is the open-source platform to build, deploy, and orchestrate AI agents. Over 70,000 developers — from early-stage startups to the U.S. Department of Defense — use Sim to turn ideas into production-grade agentic workflows on a visual, Figma-like canvas. We connect to 1,000+ apps and LLMs, and our Copilot is the state of the art for building workflows with natural language.</p>
<p>We're a team of 5, YC X25, and backed by a $7M Series A led by Standard Capital with participation from Paul Graham, Perplexity, SV Angel, and Y Combinator. We're based in San Francisco and build in-person every day.</p>
<p>Our mission is simple: agents will run the world, and Sim is the primary means by which that happens.</p>
<h2>About the Role</h2>
<p>You'll own end-to-end development of our core agentic workflow engine and Copilot — the AI assistant that helps developers build and debug workflows using natural language, turning high-level intent into executable, reliable agents. This spans our backend (Next.js), orchestration layer, and all integrations with LLMs and external APIs.</p>
<p>Copilot is currently the best-in-class tool for building workflows with natural language. Your job is to keep it there and push it further — making it faster, more reliable, and capable of handling increasingly complex agentic architectures.</p>
<p>This is a foundational role. You'll set architecture decisions, reliability standards, and coding patterns that define how the core product works. On a team of 5, your work ships to tens of thousands of developers on fast release cycles.</p>
<h2>What You'll Do</h2>
<ul>
<li>Own the agentic workflow engine: the runtime that executes multi-step, tool-using agent workflows in production</li>
<li>Build and evolve Copilot — our natural language interface for creating, editing, and debugging workflows</li>
<li>Design and maintain integrations with LLM providers (OpenAI, Anthropic, Google, local models via Ollama) and external APIs</li>
<li>Architect the orchestration layer that turns visual flows into reliable, observable agent executions</li>
<li>Set technical standards for the codebase — reliability, testing, code quality, and architecture patterns</li>
<li>Work across the stack in our Next.js monorepo, shipping to production daily</li>
<li>Debug hard problems at the intersection of LLMs, distributed systems, and developer tooling</li>
</ul>
<h2>What We're Looking For</h2>
<ul>
<li>Strong generalist engineer who has shipped complex distributed systems or developer tools to production</li>
<li>Deep experience with TypeScript/JavaScript and Bun; comfort working in a Next.js monorepo</li>
<li>Track record of owning and operating production systems — you've been paged, you've debugged the weird ones, you've made things reliable</li>
<li>Experience integrating with LLMs or building on top of foundation model APIs</li>
<li>High agency and ownership — on a team this small, you define the roadmap as much as you execute it</li>
<li>Strong opinions on architecture, loosely held — you care about building things right but move fast</li>
<li>Experience with AWS infrastructure is a plus</li>
<li>Contributions to open-source projects are a plus</li>
</ul>
<h2>Why Sim</h2>
<ul>
<li>
<strong>Foundational impact.</strong> You're not joining a team — you're building one. Every decision you make shapes the product and the company.</li>
<li>
<strong>Real users, real scale.</strong> 70,000+ developers use Sim today. Your work ships fast and matters immediately.</li>
<li>
<strong>World-class backers.</strong> Series A - Standard Capital, Paul Graham, Perplexity, SV Angel, and Y Combinator believe in what we're building.</li>
<li>
<strong>Open source at the core.</strong> We've been open source from day one and we're proud of it. 26,000+ GitHub stars and growing.</li>
<li>
<strong>Competitive salary + meaningful equity.</strong> Early team, significant ownership.</li>
<li>
<strong>Full benefits.</strong> Comprehensive health insurance, relocation.</li>
<li><strong>Visa sponsorship available.</strong></li>
</ul>