Senior Backend Engineer (Main Application Team)

Rohlík Group is one of Europe’s fastest-growing online grocery platforms, changing how people eat and live. Founded in 2014 in the Czech Republic, we’ve grown into a trusted brand with more than one million customers across Czechia, Hungary, Austria, Germany, and Romania. Our mission is simple to make everyday shopping faster, easier, and more sustainable. We combine smart technology, efficient logistics, and a genuine love for great food. From local bakeries and farmers to our own private labels, we make sure every product that reaches our customers is fresh, safe, and top-quality. We’re committed to sustainability and supporting local communities, reducing packaging, and working closely with small producers. For our customers, Rohlik Group is more than just shopping, it's a better way to enjoy good food every day. DEPARTMENT OVERVIEW The Software Development team designs, builds, and maintains our in-house e-grocery platform. We work in agile, cross-functional squads to scale our services, enhance mobile and web user experiences, and support seamless end-to-end automation across our logistics networks. Our engineering culture focuses on high performance, continuous delivery, and pragmatic, customer-centric innovation. ROLE OVERVIEW As a KMP Engineer, you will drive the development, scalability, and quality of our multiplatform and native Android and iOS application architecture across multiple European markets. Operating within an agile, cross-functional squad (ShapeUp), you will champion the delivery of high-value features that directly simplify customer lives and elevate the online grocery shopping experience. This role serves as a technical anchor, collaborating with Product Owners, Designers, and backend engineers to share business logic seamlessly across platforms while mentoring team members to elevate overall engineering excellence. WHAT WE EXPECT FROM YOU / THE POSITION TO PERFORM * Owns the design, execution, and deployment of shared multiplatform code and features using Kotlin Multiplatform (KMP) and Jetpack Compose. * Leads code quality, architecture scalability, application performance tuning, and the technical mentorship of engineering peers through code reviews and pair programming. * Partners with Product Designers and Product Owners to define technical scopes, run product experiments, and build highly intuitive, customer-centric mobile experiences. * Provides input to continuous delivery workflows, engineering process updates, and CI/CD pipeline optimizations (Firebase, GitLab). * Supports cross-functional frontend, mobile, and backend teams to minimize platform architectural complexity and enforce clean engineering standards. WHAT WE LOOK FOR / WHAT WE REQUIRE Required * 5+ years of professional engineering experience developing commercial Android applications. * Proficient expertise in Kotlin, Android Architecture Components, Coroutines, Flow, and Jetpack Compose. * Strong track record of maintaining high-quality code through robust automated unit testing. * AI proficiency and adoption on daily basis * Pragmatic engineering mindset focused on delivering value without over-engineering solutions. * Excellent communication and collaboration skills to operate successfully within cross-functional teams. * Hands-on experience with Kotlin Multiplatform (KMP) * Experience integrating dependency injection frameworks (Koin) and network libraries (Retrofit, Ktor). Preferred * Practical familiarity with setting up and maintaining mobile CI/CD pipelines (Firebase, GitLab). * Background in fast-paced e-commerce or high-throughput logistics software environments. * Experience with iOS WHAT’S IN IT FOR YOU * Fair reward - You’ll get a strong fixed salary, no bonus games, no politics. Great work is rewarded clearly and fairly. * Good food every day - You’ll enjoy a free lunch every day and fresh fruit & veggies in the office. Because good food fuels great work. * Life, not just work - You’ll have real flexibility three days in the office, 2 days at the Home Office where it suits you. And unlimited paid vacation based on trust. * Personal growth - You’ll grow as fast as Rohlik does. Every challenge is a chance to learn and make an impact. * Real impact - What you do here matters. You’ll see your work changing how people eat and live from day one. * Recognition among colleagues - Your effort won’t go unnoticed. You can recognise others (and be recognised) through peer credits to use in our internal cafeteria. * Xtra membership - You’ll get free Xtra membership and 10% cashback on everything you buy on Rohlik.cz. * Sport & wellbeing - You’ll stay active with company sports challenges or a subsidised Multisport card. * A team that sticks together - You’ll work with people who move fast, support each other and celebrate wins together. * If this sounds like you - You’re someone who takes ownership, acts fast and gets things done. Ready to bake something great with us?

ABOUT THE PROJECT We’re building Prometheus: autonomous drone swarms designed for GPS-denied and signal-denied environments—with no pilot, no constant radio link, and no external compute. The goal is simple: when drones stop being tools and start being teammates. Instead of “programming missions”, operators state intent—“Search the second floor.” “Map the west wing and find trapped people.”—and the swarm executes, returns to dock, recharges, and continues. We’re now moving from “it works” to reliability, productization, pilots, and real deployments—that’s the phase where great engineering matters most. Example of our work: THE ROLE You’ll own the next-generation Prometheus drone hardware and the dock. Your job is to take what a small team prototyped and turn it into something we can confidently put into customers’ hands for industrial inspection / indoor operations, with 24/7 capability via docking + self-charging or automatic battery hot-swap. This is a builder role: design → prototype → break → iterate → harden → repeat. Minimal meetings. High ownership. This is not a research-only role. In the early phase, you will also build and assemble drones and docks for customers in low volumes, take responsibility for practical quality checks, and fix things that break in the field. Over time, manufacturing will move to a dedicated process/team, but initially this role includes hands-on building, testing, and pragmatic QA. This role is focused on raising technology readiness (TRL) — turning prototypes into repeatable, reliable hardware suitable for pilots and early customers, not exploratory research. KEY RESPONSIBILITIES: Airframe & endurance * Design the next drone iteration focused on meaningfully longer mission time, stability, robustness, and serviceability (current version V1 can be seen here: https://www.goodai.com/swarm-robotics/ ). * Drive propulsion/weight/thermal tradeoffs with explicit budgets (mass, power, noise, cooling, crash energy, etc.). * Design for close-to-obstacles indoor flight with protections (guards, bump tolerance, maintainability). Docking & energy replenishment (core) * Own the dock mechanical system and the drone-side interface: * precision landing guidance & alignment features * contact charging OR inductive charging OR automatic hot-swap interface (your recommended solution) * safe retention/locking, E-stop behaviors, fail-safe states * Design for repeated cycles, dirt/dust, misalignment, and abuse. Hardening for customer environments * Turn prototype “works in our observation space” into “works reliably for pilots and customers”: * shock/vibration, protective structures, connectors, cable management * repairability: fast swap of arms/guards, modular components * environmental constraints: dust, temperature, light smoke residue, etc. Engineering process (lightweight, but real) * Implement DFM/DFA thinking early (fast assembly, reduced part count, reliable fasteners, tolerances). * Define acceptance tests, reliability tests, and a “flight hours → failures → fixes” loop. * Own suppliers for mechanical parts and iterate rapidly (3D print, CNC, composites—whatever fits). * Comfort defining and tracking basic quality metrics (failure rate, repair time, cycle count). WHAT SUCCESS LOOKS LIKE (FIRST 3–6 MONTHS) * A clear hardware roadmap with 2–3 staged prototypes (alpha → hardened alpha → pilot unit). * A new drone iteration with clearly improved flight time (e.g. via batteries, propellers, airframe efficiency, mass reduction), backed by measurements—not just theory. * A working dock prototype with repeatable autonomous cycles and a realistic path to production. * A documented energy replenishment decision (charge vs swap), backed by a test plan and early validation. * Measurable improvement in endurance, repairability, and “ops friction” (setup time, swap time, failure rate). TRIAL PERIOD AND EVALUATION (FIRST 4 MONTHS) This role has a clear trial period with explicit expectations and fast feedback. * Progress is reviewed weekly directly by Marek. * We prefer to end things early rather than let misalignment drag on. Expected trajectory during the trial period: Weeks 1–4 * Rebuild and iterate on the current V2 drone. * Show fast execution: first working hardware improvements in days, not weeks. * Demonstrate the ability to choose a direction, finish, and not get lost in options. Weeks 5–10 * Deliver a more substantial iteration (informally “V3 direction”): * improved flight time * better robustness and serviceability * cleaner assembly and repair flow Weeks 11–16 * Design and prototype the docking station (charging or hot-swap). * Validate core assumptions with real hardware tests. * Show that you can converge on a reliable solution, not just explore concepts. If progress stalls, iteration speed is low, or ownership is missing, we will not wait months to make a decision. REQUIRED PROFILE (MUST-HAVE) * Strong mechanical/mechatronics engineering skills with real shipped hardware, not only research prototypes. * Excellent 3D modelling tools (CAD, Fusion360 or similar)  * Experience with industrial design  * Hands-on prototyping: 3D printing, workshop tools, fast iteration, debugging physical systems. * Ability to design systems that survive repeated use: connectors, mounts, retention, wear, vibration, shock. * Independence: you can take a vague goal, turn it into requirements + design + test plan, and execute. GOOD TO HAVE * UAV or high-dynamics robotics experience (propulsion, vibration, weight/power budgets). * Docking/charging/hot-swap systems (robots, drones, warehouses, consumer devices). * Basic electronics integration literacy (you don’t need to be an EE, but you can work with one). * Ability to write and debug firmware/software for embedded systems * Experience with CFD, basic understanding of aerodynamics  * Reliability tools: FMEA, HALT/HASS mindset, design of stress tests, failure analysis. * Manufacturing exposure: contract manufacturers, supplier management, assembly line thinking. * Comfort using modern AI tools (e.g. LLMs, AI coding assistants) for faster iteration, documentation, analysis, and problem solving. THIS WILL BE A BAD FIT IF…  * You prefer long planning cycles over building and testing hardware weekly. * You avoid ambiguity and need fully specified requirements before starting. * You don’t enjoy owning systems end-to-end (design → build → test → field failures → fixes). * You’re here mainly for research novelty rather than hardening and shipping. WHAT YOU’LL FIND AT GOODAI: Impact * Build a real-world autonomous drone-swarm platform with measurable field deployments. You’ll own a core subsystem of a category-defining product: LLM-first, swarm-first, full-stack control, reliability-obsessed autonomy. * The tech matters: autonomy in GPS/signal-denied environments is strategically important, and we’re building it in Europe. * Small team, high impact. If you like building real machines fast, you’ll fit. How we work * on-site Prague 6: limited home office * Low bureaucracy, fast decisions, direct access to founder Time off & wellbeing * 5 weeks’ vacation * Flexible sick leave Workspace * Modern offices at Oranžerie, Prague — quiet focus zones, beautiful garden, great daylight, quality equipment, bike storage, gym and shower, fully stocked kitchen, lunches prepared by our private chefs Community * Regular team breakfasts, workshops, and relaxed meetups (BBQ, game nights, parties, teambuildings)