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 Senior HR Business Partner to support our Engineering and Product teams. This is a role for someone who wants to be close to the business. You’ll work directly with leaders and managers on the people decisions that matter most as their teams grow: developing exceptional talent, building stronger managers, designing organizations, raising the performance bar and solving difficult people problems quickly. You’ll also help build the systems behind that work. Mercor is still early, and many of the development programs and talent practices we need do not exist yet. We’re looking for someone who has built from 0 to 1 before and is excited to do it again. WHAT YOU’LL DO - Partner directly with Engineering and Product leaders on talent, organizational and people decisions. - Coach managers on performance, feedback, team effectiveness, development and difficult employee situations. - Identify what our highest-performing employees need to continue growing at Mercor and turn those needs into practical development opportunities. - Build development programs from 0 to 1, from identifying the problem through design, launch, adoption and iteration. - Partner with leaders on organizational design, role clarity, succession planning and talent movement as teams scale. - Run talent and performance processes for EPD while keeping the focus on judgment and outcomes rather than process for its own sake. - Spot patterns across teams and turn them into clear recommendations for leaders and the People team. - Work across Recruiting, People Operations and the broader People team to solve problems end to end. - Move quickly between strategic questions and hands-on execution. You should be equally comfortable advising a senior leader and building the first version of something yourself. WHAT WE’RE LOOKING FOR - 8+ years of strong HRBP experience: You have substantial experience partnering with Engineering, Product or similarly technical organizations and can build credibility with senior technical leaders. - Startup experience: You’ve worked in a fast-growing startup and understand the pace, ambiguity and changing needs that come with it. - 0→1 builder: You have personally built and launched development, talent or manager programs where little or no infrastructure existed before. - Excellent judgment: You can work through complex people situations, identify what actually matters and make clear recommendations without relying on a playbook for every answer. - Manager coach: You can make managers better, including experienced leaders who expect their HR partner to challenge their thinking. - High performance orientation: You know how to differentiate performance, develop exceptional people and address performance issues directly. - Operator mindset: You are comfortable creating the strategy and doing the work required to get it into practice. - Low-ego and direct: You communicate clearly, earn trust quickly and care more about getting to the right answer than owning the answer. - In-person: You are able to work from our San Francisco office five days a week. WHY MERCOR You’ll have the opportunity to shape how Engineering and Product teams develop as Mercor scales, while building many of the underlying People systems for the first time. This is a high-ownership role with direct access to leaders and the ability to see the impact of your work quickly.