Software Engineer, Search Systems - Code Data

The posting, as Mercor wrote it

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

Some of the most valuable work on Mercor's platform is code—the tasks, problems, and solutions that train and evaluate the world's frontier coding models. As a Software Engineer for Code Search & Retrieval, you'll own the architecture and algorithms behind how we search across code tasks: finding similar tasks, routing them to the right models, and turning natural-language questions into precise retrieval.

Searching over code is a genuinely hard problem. Identifying similar code tasks—not just similar text—requires retrieval that understands structure, semantics, intent, and difficulty, far beyond what generic embeddings capture. You'll own that end to end: the vision is to search across code tasks at scale, identify and select the correct code-specific models for a given task, and translate NLP questions into search queries that return the right code and tasks.

This is a hands-on technical leadership role, not a management role. You'll design and build the retrieval systems that combine dense (code) embeddings and lexical (BM25) signals, and make the tradeoffs that let search stay fast and affordable at scale. Because Mercor operates at the frontier of data and models, you'll also own the hardest part of the problem: continuously evolving embeddings, models, and search quality as newer, state-of-the-art code models arrive—without regressing what already works.

As an engineer, your impact extends well beyond your own commits. You'll set the technical direction the rest of the org builds on, mentor and grow the engineers around you, and raise the bar for how we build.

WHAT YOU'LL DO

• Own the architecture of Mercor's code search and retrieval systems end to end—hybrid retrieval combining dense code embeddings and BM25, candidate generation, ranking, and re-ranking over code tasks.
• Solve the hard problem of identifying similar code tasks—retrieval that captures code structure, semantics, intent, and difficulty rather than s

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• Excellent systems fundamentals: distributed systems, data modeling, and API design at scale.
• Demonstrated technical leadership and mentorship—you've helped junior and senior engineers grow and level up an engineering team.
• Genuine excitement for agentic development and new technology, fluency with modern AI dev tools (e.g. Claude Code, Cursor, Copilot), and a deep passion for writing great code.
• Excellent communication—able to make complex tradeoffs legible to both engineers and leadership. Strong opinions, loosely held. High ownership, pragmatism, and a bias toward shipping.

NICE TO HAVE

• Experience training or fine-tuning code embedding models or code-specific LLMs.
• Experience with learning-to-rank, semantic search, or recommendation systems in production.
• Familiarity with LLM-based retrieval, RAG patterns, and model routing/selection.
• Background operating latency-critical services on modern cloud and orchestration infrastructure.

WHY MERCOR

• Impact: Own the code search systems that decide how well Mercor finds, routes, and evaluates the code tasks training the world's frontier models, at a company scaling faster than almost any in its category.
• Ownership: Org-wide technical scope with a direct line to engineering leadership and real authority over technical direction.
• Learning: Work alongside world-class engineers, product leaders, and AI researchers building at the frontier of AI.
• Growth: Shape the engineering organization itself—its standards, its architecture, and its next generation of technical leaders.

BENEFITS

• Generous equity grant vested over 4 years
• Up to $15K relocation bonus (if moving to the Bay Area)
• A $10K housing bonus (if you live within 0.5 miles of our office)
• A $1.5K monthly stipend for meals
• Free Equinox membership
• Health insurance

Mercor is an equal opportunity employer. We work in-person five days a week in our San Francisco office.