Full-Stack Software Engineer at Mercor

Full-Stack Software Engineer | $50–$80/hr | Worldwide Remote

Mercor is looking for an experienced full-stack engineer to help advance the frontier of AI. In this role, you'll design precise product specifications, build reference implementations, and create evaluation tasks that benchmark cutting-edge AI models. If you thrive on technical rigor and enjoy working at the intersection of software engineering and AI, this is an exciting opportunity for you.

Key Responsibilities

• Write detailed product specifications precise enough for a competent engineer to build from, and unambiguous enough to support automatic grading.
• Build complete reference implementations for each specification, ensuring all defined criteria are met.
• Author browser-driven acceptance criteria that verify real, user-visible behavior rather than implementation details.
• Calibrate task difficulty by running frontier AI models against your tasks and tuning until results land within the target performance band.
• Verify that each task fails cleanly against an empty repository, ensuring no criterion can be satisfied without genuinely building the feature.

Ideal Qualifications

• 3+ years of professional full-stack engineering experience, with a track record of shipping and operating web applications.
• Fluency in at least one modern frontend framework and one backend runtime, with working comfort across several ecosystems.
• Hands-on production experience with auth, permissions, payment flows, and file uploads — including a solid understanding of where each typically breaks.
• Strong ability to specify systems precisely in writing; the specification and its criteria are the core deliverable.
• Comfort with Docker, Git at the commit level, and command-line tooling.
• Bonus: Prior experience building evaluations, benchmarks, or test suites for AI systems is a strong plus.