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 The Applied AI org builds the systems that turn human expertise into training data for frontier models, task pipelines, expert workflows, evaluation infrastructure, and the services that tie them together. We have synthetic pipelines and modular quality control systems that run in unison to generate highest quality tasks and at scale. All of it runs on backend systems that have to stay correct, fast, and observable while the volume behind them grows every month. As a Software Engineer on Backend Systems, you'll own services in that stack: designing the data models, building the APIs, services, data pipelines that move work through the platform. This is a build role. You'll take a problem that's roughly scoped, make the design calls, ship it to production, and own it afterward. We're hiring for depth in backend fundamentals rather than any particular domain. If you've built and operated real services, handled the schema migration that couldn't take downtime, found the query that fell over at 10x traffic, designed the retry logic that made a flaky dependency invisible to users, or build a system that recover when things break that's the experience that matters here. You'll work with a talent dense group of engineers who will review your designs and push your thinking, and you'll be expected to grow into owning larger surfaces quickly. WHAT YOU WILL DO - Design, build, and operate backend services in the Applied AI stack including APIs, data models, background jobs, and the pipelines that connect them. - Own features end to end: scope the problem, write the design, ship the code, instrument it, and keep it healthy in production. - Build and tune high-throughput data and job pipelines: queuing, batching, idempotency, retries, and backpressure. - Make the system fast and reliable by adding failure recovery in pipelines, profile hot spots, Agent token and cost attribution, caching issues, and set latency, error, cost budgets you actually hold to. - Instrument what you ship: observability, metrics, logging, tracing, and alerts that proactively catch problems. - Work on modern cutting edge tools, libraries and frameworks. - Manage and launch 10s of 1000s of containers, sandbox environments, manage resource allocation and system health. - Manage infrastructure as code using Terraform. - Participate in on-call for the systems you own, debug production incidents, and write up what you learn in RCCA. - Write clear design docs and give useful code review, we make technical decisions in writing and expect everyone to take part. - Work directly with product, operations, and research partners to turn ambiguous requirements into systems that ship. WHAT WE ARE LOOKING FOR - 2–5 years of professional backend engineering experience building and operating production systems. - Strong fundamentals in backend engineering: data structures, algorithms, concurrency, and writing code that's clear enough for the next person to change. - Hands-on experience with API design - REST, gRPC, or GraphQL, and an understanding of versioning, contracts, and backward compatibility. - Solid database skills: relational data modeling, indexing, query performance, transactions and isolation, and safe migrations. Familiarity with at least one NoSQL or key-value store and when it's the right choice. - Practical experience with distributed systems basics: queues and event streams, caching, idempotency, rate limiting, and designing for partial failure. - Experience with Data Orchestration and workflow management systems like Airflow, Temporal, Dagster. - Be able to roll your sleeves up and dig deeper into the lower level infrastructure issues container, permissions, logs, traces and find the needle in the haystack. - Experience running services in production: containers, CI/CD, monitoring and alerting, and debugging issues under real traffic. - Comfort with ambiguity you can take a loosely defined problem, ask the right questions, and come back with a plan. - Genuine excitement for agentic development and new technology, fluency with modern AI dev tools (e.g. Claude Code, Cursor, Copilot), and a real passion for writing good code. - Clear written and verbal communication. High ownership, pragmatism, and a bias toward shipping. NICE TO HAVE - Experience building or integrating with LLM-backed services in production (evaluation, orchestration, or serving). - Familiarity with AI infrastructure providers like Modal, Fireworks, Baseten, Temporal BENEFITS - Bi-annual performance bonus structure - Generous equity grant vested over 4 years - Up to $15k Relocation bonus - $10K housing bonus (if you live within 0.5 miles of our office) - $1.5K monthly stipend for meals - Free Equinox membership - $200 monthly laundry reimbursement - $200 monthly personal wellness reimbursement - Health, Dental, Vision insurance