Junior Software Engineer

Junior Software Engineer at Molecule.one (Kraków, Poland)Who we are 👩‍💻👨‍💻 The average cost of developing a new drug is over $1 billion. A crucial aspect that impedes such research is the unpredictability of chemistry — it takes lots of human effort to figure out how to make a potential drug candidate. Our mission at molecule.one is to solve the unpredictability of chemistry by leveraging AI. We believe that by combining our state-of-the-art machine learning models with public and proprietary chemistry data. Most recently, together with OpenAI, we demonstrated something we're very proud of: the first chemistry discovery where an AI model proposed a novel experiment that then held up in the lab. What made it work at that speed was automation, letting us run multiple experimental cycles in the time a study like this normally takes to run once. In December 2025, we also entered into a multi-year strategic agreement with W. R. Grace, a leading global supplier of specialty chemicals, to develop new, scalable ways to manufacture chemical compounds, starting with peptide building blocks. This builds on years of work. We developed the first commercially available chemical synthesis planning software entirely based on deep learning models, and were the first start-up from Central and Eastern Europe to debut on the TechCrunch Disrupt SF stage in 2019. In 2021, we closed a funding round of 4.6M USD supported by top US & European investors. In August 2023, we announced our strategic collaboration with CAS — the owner of the world's largest database of chemical reactions — to develop the world's best platform for Synthetic Accessibility Scoring. In June 2025, our retrosynthesis platform was named the winner of the $1 million Chemical Innovation Challenge organized by Standard Industries. We are currently developing the Maria platform, which unites AI, an automated microliter-scale HTE lab, and proprietary data into a single system. Guided by our data and AI models, the lab can produce molecules with far fewer failed attempts and at a fraction of the cost of conventional laboratories. The reactions it runs generate a unique dataset that we feed straight back into the model, closing the loop: the AI proposes experiments, the lab runs them cheaply and at scale, and the resulting data makes the AI better at proposing the next ones, giving us a system that keeps improving with every reaction it runs. Building that system is exactly what the Maria team does — the team we're hiring you to join. We are a cross-domain team of people from different backgrounds, such as organic chemistry, software development, and machine learning. Currently, we have almost 30 people on board and counting! 💪 Read more about our core values on the careers page. What will you work on? 🧭 Expect real variety: we tackle everything from scientific puzzles to product features — so you'll constantly learn, ship, and make an impact across the stack. Helping build software solutions for complex scientific workflowsDesigning and implementing server-side services & APIsParticipating in UX and product design discussionsDesigning and implementing data pipelines that connect lab workflows with our softwareHelping deploy and run machine learning models in production — packaging, serving, and monitoring them as part of our platformBuilding, testing, and refining AI agents that automate parts of our internal processes — from lab workflows to engineering toolingWe take pride in making sure everyone's voice is heard, and we plan our quarterly and yearly goals together. You'll be given growing independence and support while working in a cross-disciplinary team full of smart — and nice! — people. You'll report to your team lead. To understand better how we work, please read the values section on our careers page. Your profile 👤 We're looking for someone with a pragmatic approach to code and a humane approach to people. While we don't believe in years of experience, we're looking for someone who enjoys learning fast and gradually taking ownership — with support from experienced teammates, regular feedback, and plenty of room to grow. As an ideal candidate, you should have: Curiosity, critical thinking, and problem-solving skillsAbility to take ownership of well-scoped tasks, ask good questions, and follow throughOpenness to using AI coding tools thoughtfully, with a critical mindset toward generated codeExperience with TypeScript or Python, and willingness to learn the otherKnowledge of basic programming paradigms, best practices, algorithms, and data structuresInterest in working hands-on with LLM-based agents — designing prompts, tools, and evaluation loopsYou are a high agency person (https://www.highagency.com/). You are not scared to question authority, propose your own solutions, and work independentlyCommunicative English (B2 level) Nice to have: Additional background in chemistry 🧪, physics ⚛️ or biology 🧬Experience with declarative JavaScript frameworks (we use React)Some experience in infrastructure management (e.g. CI pipelines, Dockerization, Kubernetes)Familiarity with modern development tooling & ecosystemInterest in product strategy and cross-disciplinary collaboration What we offer 🎉 💵 Junior: 10 000 - 14 000 PLN gross per month on a Contract of Employment, or an equivalent on B2B🕒 Full-time position with immediate start date.🔭 An opportunity to work on novel and exciting problems.💻 All the equipment you need.⏱️ Flexible work hours and hybrid work model — our office is in Kraków (Kraków Technology Park), with flexibility to work remotely part of the week📝 Opportunity to publish and present your work at top venues.👥 A top team that will inspire you to be your best self.💰 Equity package (after the probation period) 💡 Interested? Please reach out to us via email: dev.recruitment@molecule.one by 21/08/2026. We will start scheduling the first interviews from 17 August 2026, so the sooner you apply, the sooner we can talk. We can't wait to meet you and discuss the great things we can achieve together! Please do not forget to add to your resume the following clause: I agree to the processing of personal data provided in this document for realizing the recruitment process pursuant to the Personal Data Protection Act of 10 May 2018 (Journal of Laws 2018, item 1000) and in agreement with Regulation (EU) 2016/679 of the European Parliament and of the Council of 27 April 2016 on the protection of natural persons with regard to the processing of personal data and on the free movement of such data, and repealing Directive 95/46/EC (General Data Protection Regulation). The hiring process at Molecule.one ☕ ↗️ Our hiring process consists of several stages. After each stage, we will either invite you to the next stage or discontinue the process. In the latter scenario, we will also give you feedback. The whole recruitment process is conducted in English. 0. CV Screening As the first part of the process, we ask you to send us your CV. After examining your CV, we will invite you to the first interview. We accept applications until 21 August 2026 and will start scheduling the first interviews from 17 August 2026 — we review applications as they arrive, so please apply as early as you can. 1. Introduction interview The first interview will last up to 30 minutes and take place online. During this interview, one of our team members will ask you a few questions about software development and your experience so far. 2. Programming assignment After the first interview, we will send you a short programming assignment. This assignment should take at most a couple of hours to complete. We will ask you to send us the completed assignment within four days of receiving it. 3. The final interview After receiving and reviewing your programming assignment, we will invite you to the final interview. This interview can be conducted online or on-site in our Kraków office, depending on your preference. The interview will last up to 90 minutes and involve some questions about your assignment solution, as well as more in-depth discussions about your experience in software development. ✨ Interested? Please reach out to us via email: dev.recruitment@molecule.one We can't wait to meet you and discuss the great things we can achieve together!