RL Engineer

About This Opportunity

About Ethos
We're building AI to make humans irreplaceable. Ethos is the platform that matches human expertise to paid opportunities, from AI model training to advisory roles and full-time positions, backed by a16z, General Catalyst and other top investors.

Key Requirements

• Hands-on experience building RL environments or generating data for post-training (RLHF, RLAIF, preference data, evals) — this is central to the role
• Startup experience — you've shipped in resource-constrained environments and taken real ownership
• Strong background building AI/agentic applications (LLM pipelines, tool use, evals)
• Generalist instincts - you'd rather solve the problem than protect your lane
• Comfortable across the stack: backend, infra, and ML tooling