Founding Product Engineer (Full Stack)

About B12

B12 is building an AI-native software platform for chemistry.

Our products help scientists move from a target molecule to a synthesis plan, design experiments, and translate those experiments into workflows for automated laboratories. The platform combines scientific software, AI agents, data infrastructure, and real lab automation.

Today, b12 Labs supports 5 of the top 10 largest pharma companies, running chemistry faster each week. You will help us further grow that usage and improve the overall experience in the platform.

We have built the core technology. Now we need an exceptional engineer to make the entire product feel fast, dependable, and coherent for customers.

The role

We are looking for a Founding Product Engineer who will take end-to-end responsibility for the b12 Labs’ SaaS platform.

You will work across the frontend, backend, infrastructure, and AI systems. You will work directly with the founders, scientists, and customers. You will have substantial influence over the product, technical architecture, and engineering culture.

What you will own

- The reliability, performance, and usability of our customer-facing SaaS platform

- Features from initial product definition through implementation, deployment, monitoring, and iteration

- The interfaces connecting our AI agents, scientific applications, databases, and long-running workers

- Authentication, permissions, persistence, task execution, streaming updates, and failure recovery

- Product quality across retrosynthesis, experiment design, scientific data analysis, and laboratory automation

- Debugging difficult issues using production evidence rather than assumptions

- The engineering systems that help us ship quickly without sacrificing reliability

- Direct conversations with users to understand what is broken, confusing, or missing

Our current stack includes React, Vite, Python, FastAPI, PostgreSQL/Supabase, AWS, asynchronous workers, and multiple AI model providers. You do not need to know every part of the stack already, but you should be able to learn unfamiliar systems quickly.

What we are looking for

- At least 3 years of professional software engineering experience

- Evidence that you have shipped and operated real software used by customers

- Strong full-stack ability, with particular depth in backend systems and product reliability

- The ability to take an ambiguous customer problem and drive it to a working, polished result

- Good judgment about architecture, trade-offs, testing, and when to simplify

- Experience diagnosing failures across frontend, API, database, background jobs, and infrastructure

- High standards for product design and user experience

- Comfort working with AI coding tools and agent systems without depending on them for engineering judgment

- Unusually high curiosity and learning velocity

- Clear communication and a strong sense of personal responsibility

We care more about what you have built and owned than where you studied or which companies appear on your résumé.

Especially valuable

- Experience building scientific, technical, or data-intensive products

- Distributed systems, job queues, streaming interfaces, or long-running workflows

- PostgreSQL data modeling and production operations

- Cloud infrastructure and observability

- Applied ML, AI agents, or AI-for-science research

- Chemistry, cheminformatics, laboratory software, or a genuine desire to learn the domain

- Strong product design instincts

Chemistry experience is helpful but not required. Intellectual curiosity about science IS required.

This role may not be a fit if

- You want narrowly defined tickets rather than broad ownership

- You prefer prototypes but are not interested in operating production systems

- You view frontend quality, customer support, infrastructure, or debugging as someone else’s responsibility

- You need complete specifications before beginning

- You are excited by AI demos but not by the engineering required to make them reliable

Why join

You will work on software where better engineering can directly accelerate scientific discovery and reduce weeks of manual work in the laboratory. You will join early enough to shape the product and company, while working on technology that already spans AI, chemistry, and physical automation.

The founding team

b12 Labs was founded by Zlatko Jončev and Andres M. Bran.

Zlatko brings deep experience in organic synthesis, catalysis, medicinal chemistry, and laboratory automation. Andres builds AI agents for chemistry and systems that translate scientific intent into executable laboratory workflows.

Between us, we have worked at Roche, Chemspeed, the Max Planck Institute, and EPFL, where we helped pioneer AI agents for chemistry and retrosynthesis.

We started B12 after repeatedly seeing the same problem: scientists had powerful instruments and increasingly capable AI models, but fragmented software still forced them to connect every step manually—or become programmers just to operate their laboratories.

We are building the unified software layer we wished existed: from synthesis planning and experiment design through robotic execution.

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Interview Process

A 30-minute conversation with a founder about B12, the role, what you want to build, and whether our expectations match.

60-minute technical and product discussion about a system you personally shipped. We will explore your decisions, trade-offs, failures, debugging process, and what happened after launch.

A short, paid working session based on a realistic B12 product problem. This is not a LeetCode exercise. We want to understand how you navigate an unfamiliar system, clarify ambiguity, use engineering tools, and turn a customer problem into a robust solution.

References and an offer.

We aim to complete the process within 10 days. We will explain each stage in advance and provide a clear decision quickly after the final conversation.