Software Engineer, Agents

Mercor

New York (NY)

On-site

USD 150,000 - 230,000

Full time

2 days ago

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Benefits offered by this job

Bi-annual performance bonus

Equity grant

Relocation bonus up to $15k

Housing bonus $10K

Meals stipend $1.5K/mo

Equinox membership

Laundry reimbursement $200/mo

Wellness reimbursement $200/mo

Health, Dental, Vision insurance

Job summary

Mercor is seeking a strong engineer to build agentic products at scale. You will work with Backend: Python, FastAPI, Django, Pydantic; Frontend: Next.js, React, TypeScript, Tailwind; Data: PostgreSQL, MySQL, Snowflake, DuckDB, Redis; Orchestration/Infra: Kubernetes, Temporal, Modal, Woz; and Lang/LLM tools like LangGraph, LangChain, FastMCP, Harbor, NemoGym.

At Mercor you will own end-to-end features, design and ship LLM agents and pipelines, and build the infrastructure that supports frontier

Qualifications

Experience building scalable software systems
Ability to work cross-functionally with research and product teams
Strong trouble-shooting and collaboration skills

Responsibilities

Own agentic features end-to-end from scoping to rollout
Design and ship LLM agents, harnesses, and verifiers
Build Python/FastAPI services and orchestration pipelines
Develop RL environments with enterprise data and tasks
Create tooling to turn agent trajectories into insights
Develop full-stack interfaces with Next.js/React
Set quality standards and iterate on prompts, tools, and guardrails
Collaborate across Product, Design, Research and Ops

Tools

Python

FastAPI

Django

Pydantic

Next.js

React

TypeScript

Tailwind

PostgreSQL

MySQL

Snowflake

DuckDB

Redis

Kubernetes

Temporal

Modal

Woz

LangGraph

LangChain

FastMCP

Harbor

NemoGym

Datadog

PostHog

LangSmith

Job description

About Mercor

Mercor's mission is to organize human intelligence to power the AI economy. We're a leading AI data company, building the layer between human expertise and frontier models. Millions of domain experts on the platform are paid over $4 million per day to train frontier AI models. Mercor's APEX benchmark family measures AI's real-world impact on professional work. Mercor Enterprise brings this same infrastructure to Fortune 500 companies: helping companies capture how their best people actually work, translating that expertise directly back into agents. Mercor is creating a new category of work where expertise powers AI advancement. Achieving this requires an ambitious, fast-paced and deeply committed team. you'll work alongside researchers, operators, and AI companies at the forefront of shaping the systems that are redefining society. Mercor is a profitable Series C company valued at $10 billion. We work in-person five days a week in our San Francisco, NYC, or London offices.

About the Role

We're looking for a strong engineer who can build agentic products that scale. You will work with:

Backend: Python, FastAPI, Django, Pydantic
Frontend: Next.js, React, TypeScript, Tailwind
Data: PostgreSQL, MySQL, Snowflake, DuckDB, Redis
Orchestration/Infra: Kubernetes, Temporal, Modal, Woz
Agents/LLM: LangGraph, LangChain, FastMCP, Harbor, NemoGym
Observability: Datadog, PostHog, LangSmith

At the end of the process, you'll be team-matched to where you can have the most impact, on one of the following:

Automation – We build intelligent systems and agents that automate operational work at scale—handling talent management, decision‑making insights, and knowledge access—so humans can focus on higher‑level thinking. This is a newly formed, CEO‑facing team focused on 0-1 product development, with a strong emphasis on business impact. The work is highly cross‑functional, touching nearly every system across the company.
Studio – We own Mercor's evaluation system & annotation platform for RL environments and tasks. We build harnesses, agents, verifiers, and the end‑to‑end infrastructure for producing frontier data. Our mission is to scale up high quality RL environments/tasks and expand their capabilities. We work closely with researchers at frontier AI labs to jointly shape the direction of next‑generation models.

What You'll Do

Own agentic features end-to-end — from scoping with researchers/ops partners through implementation, launch, and iteration on real customer feedback.
Design and ship LLM agents, harnesses, and verifiers — including the tools, prompts, and policies that make them reliable.
Build the Python/FastAPI services and Temporal/Modal pipelines that orchestrate agent runs, human‑in‑the‑loop review and iterations.
Build state‑of‑the‑art RL environments that expand the capabilities of frontier agents, with realistic enterprise apps, simulated coworkers, and rich company data rooms that support tasks spanning hours to days.
Build tooling that turns agent trajectories into insight, from statistical analysis to automated failure mode detection.
Build and refine the full‑stack surfaces and data infrastructure — craft Next.js/React interfaces where operators and experts work with agents, evolve data models to give agents the structured context and audit trails they need.
Define agent quality and drive continuous improvement — build evals, instrument traces, analyze failure modes, and iterate on prompts, tools, and guardrails while raising the bar for reliability, cost, latency, and UX.
Partner cross‑functionally to shape agent autonomy — work with Product, Design, Research and Ops to draw the lines between autonomous action, propose‑and‑approve flows, and human‑in‑the‑loop decisions.

Why Mercor

Impact: Your work powers how the world’s leading AI labs train and test their models.

Learning: Get early insights into frontier model capabilities months before the market.

Growth: Work on both infrastructure and research‑adjacent projects with fast paths to ownership.

Benefits