Director / Senior Director of Biology

The opportunity

Codebreaker is building a modern functional genomics research engine to connect human genetic variation to cellular function at scale.

This is a player-coach role. You will lead scientists and research associates, set scientific direction, and remain close to the bench — especially when a difficult cell model, assay or screen needs to be established, debugged or scaled. You should genuinely enjoy experimental work and the craft of making complex human cell systems reliable.

You will help build high-throughput CRISPR and phenotyping workflows across challenging human cell models, including primary T cells, other primary cells, fibroblasts, and iPSC/iPSC-derived systems. You will partner tightly with computational biology and machine learning colleagues and use modern AI tools as part of your daily scientific workflow to increase the quality, speed and scope of what a small team can accomplish.

We expect this role to map to Director or Senior Director depending on experience and scope.

What you will do

• Own the design and execution of high-throughput functional genomics programs using CRISPR and related perturbation technologies in human cells.
• Build, optimize and troubleshoot robust culture and engineering workflows for technically demanding human cell systems, including primary T cells, other primary cells, fibroblasts, and iPSC/iPSC-derived models.
• Develop scalable experimental workflows spanning cell engineering, perturbation delivery, phenotypic assays, sample processing, QC and structured data capture.
• Design and execute pooled and/or arrayed genetic screens, with a strong emphasis on reproducibility, throughput, assay quality and rapid learning cycles.
• Develop and apply high-dimensional phenotyping approaches, ideally including single-cell RNA-seq and other single-cell or multi-omic readouts, flow cytometry, and functional cellular assays.
• Lead, mentor and grow a high-performing wet-lab team while remaining an active scientific contributor at the bench. Set a high bar for experimental rigor, pace, ownership, documentation and follow-through.
• Work side by side with computational biology, data science and ML colleagues so experiments produce well-structured, well-annotated, AI-ready datasets for downstream analysis and model development.
• Use AI-enabled tools and agents routinely for scientific research, coding, analysis, visualization, literature synthesis, experimental planning, documentation and workflow automation. Help the team continuously identify ways to increase output per scientist without compromising scientific quality.
• Prioritize across multiple concurrent programs, making pragmatic decisions about scientific value, speed, resource requirements and technical risk in a resource-constrained startup environment.
• Establish clear experimental standards and decision criteria; analyze and interpret screening results with appropriate statistical rigor and drive rapid follow-up experiments.
• Contribute to intellectual-property strategy, invention disclosures, publications, external scientific presentations and collaborations.
• Manage program timelines, budgets, equipment and resource needs in partnership with the VP of R&D, and serve as the initial Site Safety Officer during the company's seed-stage buildout.

What we are looking for

• PhD in immunology, molecular biology, cell biology, genomics, bioengineering or a related field, with substantial postdoctoral and/or industry research experience.
• Exceptional hands-on expertise in mammalian cell culture, with demonstrated success establishing, maintaining, manipulating and troubleshooting difficult human cell models — not only standard immortalized cell lines. Experience with primary human T cells and/or other primary cells is especially valuable; iPSC or iPSC-derived cell experience is highly desirable.
• Deep practical experience with CRISPR-Cas9 or related genome-engineering technologies in human cells, including optimization of perturbation delivery and editing workflows.
• Experience designing and executing high-throughput pooled and/or arrayed genetic screens, or similarly scaled cell-based experiments.
• Strong experimental judgment and a record of turning messy biological systems into reproducible assays and decision-quality datasets.
• Experience with single-cell sequencing or other high-dimensional cellular phenotyping is strongly preferred; scRNA-seq, flow cytometry, functional immune assays and multi-omic approaches are particularly relevant.
• Demonstrated people leadership and mentorship. You enjoy developing scientists, setting priorities and creating accountability — and you are equally willing to put on gloves and help solve the experiment yourself.
• High personal drive, urgency and stamina for an early-stage environment. You take ownership, move quickly, follow through, and are energized by ambitious goals rather than narrowly defined job boundaries.
• Fluency with modern AI-enabled scientific workflows. You do not need to be an ML researcher, but you should already use — or be eager to deeply adopt — AI tools for analysis, coding, visualization, literature work, experimental design, documentation and automation.
• Strong collaboration and communication skills, especially across experimental biology, computational biology, data science and machine learning.
• Comfort operating with ambiguity, changing plans when the data demand it, and balancing scientific depth with the speed required at a seed-stage company.

Especially valuable

• Direct experience with causal/functional genomics, variant-effect studies, saturation mutagenesis, Perturb-seq, or related perturbation-plus-single-cell approaches.
• Experience scaling assays through automation, liquid handling, plate-based workflows, LIMS/data pipelines, or other high-throughput laboratory infrastructure.
• Experience generating datasets specifically designed for computational or machine-learning applications.
• Track record of impactful publications, patents or delivered research programs, including contributions to patent filings.
• Experience building teams, laboratory capabilities or scientific processes in an early-stage biotech company.

Why Codebreaker

This role offers unusual scientific ownership. You will help define not just individual experiments, but how the biology organization works: which cellular systems we build, how we scale perturbation and phenotyping, how experimental and computational teams work together, and how AI changes the productivity of a modern research group.

The right person will have room to build, lead and still do science. If you are happiest when the biology is hard, the questions matter, the team is strong and the pace is high, we would like to meet you.

Compensation and benefits

Compensation: $145,000–$190,000 per year. Compensation also includes meaningful early-stage equity. Where an offer lands within the range depends on demonstrated scope, depth and prior impact.

Benefits: Competitive benefits package. Full details are shared during the interview process.