AI Systems Full-Stack Engineer — Build, Test, Innovate

Mercor; New York (NY); On-site; USD 120,000 - 180,000; Full time

Job summary

Mercor is seeking experienced full-stack engineers to work on an exciting opportunity to advance the frontier of AI. You will write precise specifications, build a complete reference implementation, and create browser-driven acceptance criteria to guarantee real user-visible behavior.

Join a team shaping scalable, production-grade AI-enabled applications. Ideal candidates combine 3+ years of hands-on full-stack work with fluency in multiple frontend and backend technologies, plus experience with

Qualifications

• 3+ years of professional full-stack engineering, having personally shipped and operated web applications.
• Fluency in at least one modern frontend framework and one backend runtime, with working comfort across several
• Hands-on experience implementing auth, permissions, payment flows, and file upload in production, and knowing where each one usually breaks
• Ability to specify a system precisely in writing: the specification and its criteria are the product
• Comfort with Docker, git at commit level, and command-line tooling
• Prior experience building evaluations, benchmarks, or test suites for AI systems is a strong plus

Responsibilities

• Write product specifications precise enough that a competent engineer could build the application, and unambiguous enough to grade automatically
• Build a complete reference implementation of each specification that passes every criterion you have written
• Author browser-driven acceptance criteria that verify real user-visible behavior, not implementation details
• Calibrate task difficulty by running frontier models against your task and tuning until it lands in the target band
• Verify each task fails cleanly against an empty repository, so no criterion can be satisfied without genuinely building the feature

Skills

Full-stack experience

Frontend framework

Backend runtime

Auth & permissions

Payment flows

File uploads

System specification writing

Docker

Git

AI evals/tests

Tools

Docker

Git

Job description

Mercor is seeking experienced full-stack engineers to work on an exciting opportunity to advance the frontier of AI. You will write precise specifications, build a complete reference implementation, and create browser-driven acceptance criteria to guarantee real user-visible behavior.

Join a team shaping scalable, production-grade AI-enabled applications. Ideal candidates combine 3+ years of hands-on full-stack work with fluency in multiple frontend and backend technologies, plus experience with