Lead Software Engineer (M/F) - CDI - Paris

Empty seats on trains. Unsold stadium tickets. Every day, the transport and events industries lose immense value due to outdated systems, blind forecasting, and rigid pricing. Founded in 2014, Wiremind is a fast-growing SaaS company specializing in inventory, ticketing and revenue management . Combining deep industry expertise with AI, data science and a modern UX, we help our clients sell their capacity across every channel and by setting the right price. We partner with leading rail operators, airlines and event organizers to transform their commercial performance via machine-learning-powered demand forecasting and agentic automation, decision-ready visualizations, and intuitive interfaces for end users, driving customer loyalty and engagement. Our applications have become the tool of choice for more than 50 clients across more than 10 countries worldwide, from passenger transport operators such as SNCF, Transavia, VIA Rail Canada and Eurostar to sports clubs such as PSG, Angers SCO and FC Sochaux , to manage their inventory, sell tickets across every channel, and optimize their pricing on a daily basis. Today, Wiremind has 170 employees and has been profitable and 100% bootstrapped since day one. We are a team of experts driven by engineering excellence and product impact. Your missions 🚀 You’ll join CAYZN, our advanced Revenue Management Solution for the transportation industry, helping our clients optimize their capacity with dynamic pricing. It offers a user-friendly interface coupled with data visualisation and powerful automation workflows with a business rules engine. Leveraging machine learning models, CAYZN is able to recommend and automatically set the best price to fill our clients' means of transportation (bus, airlines or railways). With CAYZN, our clients' revenue managers turn their pricing strategy into business rules . A business rule is a condition written by the user on service, leg, cabin, market or forecast data, that automatically adjusts prices, ancillaries or optimization settings on thousands of services. The Business Rules squad owns this engine end to end: the rule language and its parser, the evaluation engine, the variables it exposes, and the interface used to write, test and apply rules. We are looking for a Lead Software Engineer to take the technical lead of this squad. Reporting to the Head of Software Engineering of Cayzn , you will work closely with the Product Owner, Product Experts, Data Scientists and the Platform team to ship reliable and scalable features for our international clients (railways, airlines, bus operators). Technical ownership & architecture Own the architecture of the business rules engine: rule language, parsing, evaluation and performance at scale Design and develop efficient code that is easy to maintain, mainly on the backend and on the frontend when needed Own the technical decisions of the squad: refactoring, scalability, trade-offs between new features and technical debt Improve operational quality: monitoring, alerting, performance and incident follow-up Delivery & product Understand in depth how revenue managers work, to make the right implementation choices Work with the Product Owner to find the most efficient path to delivery and plan work consistently Take part in roadmap decisions to keep a good balance between refactoring, scaling work and new features Team & knowledge sharing Review code, mentor the developers of the squad and help them grow Share your knowledge, and bring in new practices, frameworks or tools where they add value Stay hands-on: around 70% of your time on development , on the most challenging parts of the codebase Technical stack: Backend : Python 3.15 , SQLAlchemy, Remoulade (in-house task queue) Frontend : Angular, TypeScript, D3.js Data-store : Postgresql, Elasticsearch, Redis Gitlab for continuous delivery Kubernetes for infrastructure Prometheus/Grafana and Kibana for operations Your profile 🔍 You have 5+ years of experience as a Software Engineer working with Python or a similar backend language on a large codebase with many contributors, and have already mentored or managed a small team of software engineers You are a builder: you love writing code, solving hard technical problems, and raising the quality bar through your own output. Strong fullstack background with a backend-first mindset (Python), fully comfortable owning frontend work (Next.js or equivalent). Good communication skills, able to collaborate with Product and align technical decisions with business priorities — without spending most of your time in meetings. Bonus: Experience in SaaS, event-tech, or working on complex interfaces and operations-heavy B2B2C products. You have a native or fluent level in French Our benefits 🤌 By joining us, you will integrate: A self-financed startup with a strong tech identity! 🧬 Beautiful 800 m² offices in the heart of Paris (Bd Poissonnière) Attractive remuneration indexed on performance A caring and stimulating team that encourages skills development through initiative and autonomy A learning environment with opportunities for evolution You will also benefit from: A hybrid policy: 2 days of remote work per week and the possibility to work occasionally from abroad 💻 Access to WellPass at a preferential rate to maintain your well-being 🏀 A great company culture (monthly afterworks, regular meetings on technology and products, annual off-site seminars, team-building…) Our Recruitment Process 🤞 A screening interview with Anne-Laure our Lead Talent Acquisition Manager An interview with Antoine, the Head of Software Engineering of Cayzn A technical test or case study to prepare A technical interview at our offices to go through your test and meet the Cayzn team A final interview with Charles ou CTO and co-founder Wiremind is committed to equality of opportunity, diversity, and fairness . We encourage all candidates with the necessary experience to apply for our job offers