Founding Engineer

Lightsage • San Francisco, CA

2d • $120,000 - $200,000 • Onsite

About The Position

Lightsage helps companies succeed in the agent economy by measuring whether AI agents and answer engines recommend them, testing how coding agents use their APIs, CLIs, and MCP servers, and identifying improvements. It works with category leaders in AI and developer tools and operates DevToolArena.com, a public benchmark for how well coding agents use developer tools. Lightsage has raised a $4M seed round led by Nexus Venture Partners.

As one of Lightsage’s first engineering hires, the Founding Engineer will join the founding team in San Francisco and own systems end to end across frontend, backend, infrastructure, and data. The role works directly with customers to turn their problems into shipped features. Early work includes improving recommendation quality and measuring the impact of changes; designing experiments and benchmarks; building agents that write, publish, and retest customer documentation; supporting new coding agents and models; and scaling evaluation and data pipelines for enterprise customers. The team uses AI coding tools and its own agent orchestrator, and reviews code before it ships. This is a full-time, on-site role with a demanding schedule that regularly includes weekends and significant ownership over the company’s technical direction.

Requirements

• Track record of taking a loosely defined customer or product problem to a shipped solution with little direction.
• Strong backend experience, including building reliable systems that handle production load.
• Hands-on experience shipping quickly with AI coding tools such as Claude Code or Codex.
• Clear thinking about technical trade-offs and clear written communication.

Nice To Haves

• Experience doing research or running rigorous experiments, such as LLM evaluations, benchmarks, or A/B tests, and drawing sound conclusions from noisy results.
• Experience with Next.js, FastAPI, Supabase, or Microsoft Azure.
• Prior founder or early-stage startup experience.

Responsibilities

• Own systems end to end across frontend, backend, infrastructure, and data.
• Work directly with customers to translate their problems into shipped features.
• Improve recommendation quality and measure whether changes help customers.
• Design experiments and benchmarks to determine which changes make agents recommend and use products.
• Build agents that write, publish, and retest customer documentation changes.
• Add support for new coding agents and models as they are released.
• Scale evaluation and data pipelines for enterprise customers.

What This Job Offers

• Job Type: Full-time
• Career Level: Senior
• Education Level: No Education Listed