(Senior) Full Stack Next.js Developer (f/m/d)

OH-SO

WHAT TO EXPECT We are a startup digital agency, and no two projects, clients, or even days look the same. In ecommerce we build on Shopify and Liquid and Next.js, with custom AWS microservices and apps that take Shopify well past the defaults.  On the marketing side we build highly customised sites in Next.js and React, with careful design and animation and a real focus on how the page performs and feels.  In automotive we build full platforms, from stock-car locators to configurators and more. Across all of it, we bring AI into the work through our own products. Here nothing will be fixed. You will work across changing projects and settings, on long builds that run for months and shorter spikes to figure out how a business can actually use AI, and you will help us rethink how agency work is done. Sound like your kind of place? Here is what we need from you. YOUR COMPETENCIES Mindset Is your goal to deliver great software, whether the problem is easy or hard? Do you push deeper than most to find the right solution, not just the first one that works? Then you are the person we need.  Responsibility You own what you build, all the way through, not just until it ships and becomes someone else's problem. The parts that go smoothly and the parts that get messy are both yours to see through. You bring your ideas and your curiosity, you use AI to build better and faster, and you stand behind what you put your name on. Drive You will not know everything yet, and that is fine. What we cannot teach is drive. We bring the tools and the guidance. You bring the push to grow fast, understand what you build, and keep reaching past what you know. What you bring to the table: * You work across crafts, not in a corner. You are close with developers, designers, and strategists, and you would rather build in the open than behind a wall. * You make the team better. You speak up when something can be sharper, and you share what you learn instead of sitting on it. * You care whether the client wins. You focus on the quality of the product and the experience, not just the ticket in front of you. WHAT YOU CAN LOOK FORWARD TO What you will actually do: We build complex, end-to-end products for both big-names and niche clients. You will own the frontend side of that work, plus the bits right next to it. Day to day, that means: * Turning designs into real interfaces in React and Next.js. * Building small pieces of UI and the logic behind them on your own, and taking on medium ones with a more senior engineer alongside you. * Working in an responsive team with clean tickets, clear updates, and knowing when to push on alone and when to ask for help. * You’re enjoying being part of a team, not a remote desk which prefers to work in isolation most of the time. The tech stack you will work with: * Languages and frameworks: React, Next.js, TypeScript, HTML, CSS * APIs: REST and GraphQL * Delivery: Existing CI/CD practices * AI tooling: Claude, Cursor, Pi, Antigravity, plus your and our own Skills and MCP setup Who you will work with We are a bunch of colleagues originally from similar backgrounds who got tired of how things were usually done and set out to find better ways. That is the whole reason this company exists, and it is still what we are doing. We are not a place of rockstars and egos. People here ask questions out loud, show rough work without flinching, and would rather help each other get something right than look clever alone. We push each other, in the good way, and we do not take ourselves too seriously while we are at it. You would be joining that. You’ll work closely with the crafts, designers and strategists, and just as easily with the people steering the projects and the business. There is no wall between you and any of it. Take on the parts you are ready for, and when you want more, a pitch, a client conversation, a bigger call, speak up at the right moment and the door is open. Smaller team. More ownership. Bigger work.

Healthtech Ventures

ÜBER UNS Healthtech Ventures (HTV) is one of Germany’s most innovative and fastest-growing digital health companies. We operate a portfolio of integrated telemedicine platforms that connect patients, doctors, and pharmacies — making modern healthcare more accessible, efficient, and patient-centered.  Our platforms — Prio One, SoLean, and Nordleaf — cover some of the most dynamic therapeutic areas, including women’s health, weight management, and medicinal cannabis. HTV combines medical expertise, digital excellence, and operational precision to deliver outstanding patient experiences and sustainable growth. DEINE AUFGABEN Your Core Missions 1. Attribution & Channel Strategy * Strategic Spend: Own the monthly, Finance-reconciled CAC and MTA models; advise exactly where the "next Euro" should be spent. * Fatigue Detection: Identify channel saturation and creative fatigue across the full mix (Meta, Google, TikTok, etc.) before they hit the P&L. 2. Onsite & Merchandising Optimization * Conversion Ownership: Use data to optimize PDP performance, recommendation logic, and checkout flows, surfacing hidden friction in prescription steps. * Scientific CRO: Lead the test backlog with the E-com Manager, ensuring every experiment has defined power, sample size, and kill criteria. 3. Data Modeling & Trust * Warehouse Power User: Write the SQL and dbt models for the core dashboard stack (Cohorts, P&L, Funnels) and define specs for Engineering. * Data Integrity: Conduct quarterly audits of the tracking pipeline (Server-side, Pixels) to ensure budget decisions are based on trusted data. 4. Retention & Lifecycle * Cohort Mastery: Analyze LTV, repurchase rates, and time-to-second-order to drive long-term growth. * CRM Synergy: Partner with CRM to build operational patient segmentations and measure Klaviyo flow performance. 5. Experimentation & Methodology * Standard Setting: Enforce rigorous testing standards (MDE, hypothesis, primary metrics) and maintain a central library of learnings. * Incrementality Specialist: Design regional holdouts and catchment-level splits to measure the true impact of brand and influencer spend. WAS DU MITBRINGEN SOLLTEST We are looking for a heavy-hitter who has navigated the complexities of data at scale. You treat analytics as a product, not a reporting function, with a relentless focus on commercial outcomes. The Non-Negotiable Requirement You must have direct experience operating the analytics function for a DTC/e-commerce business at or beyond €100M GMV. We are looking for: * The In-House Operator: Growth/Marketing Analyst at a €100M+ brand. * The Lead Agency Analyst: Owned the end-to-end model and recommendation layer for a €100M+ client. Sub-€100M experience, generalist consulting, or "dashboard consumption" does not qualify. We are testing for exposure to failure modes at scale. Your Profile * Technical Expert: Advanced SQL (raw events) and modern warehouses (BigQuery/Snowflake/dbt). You use Python/R for complex modeling and AI workflows (Claude/Cursor) to 10x your output. * The E-com Stack: Hands-on with Shopify, Klaviyo, Meta/Google Ads, and attribution layers like Klar, Northbeam, or Triple Whale. * Methodology: Expert in MMM, MTA, and incrementality testing. You know which lever to pull and when a test is statistically valid. * Soft Skills: 4+ years of experience. Self-directed, commercially minded, and fluent in English (German is a plus). What This Role Is Not * Not a Reporting Analyst: You don't just pull lists; you drive decisions. * Not a Data Engineer: Engineering maintains the pipes; you own the modeling and strategy on top of them. * Not a Junior Hire: We are specifically seeking a veteran of high-GMV environments. WAS WIR DIR BIETEN * Dedicated Focus: Enjoy a role with zero context-switching, allowing you to focus entirely on the Shopify platform. * High Autonomy: Join a high-trust environment with no layers of management, collaborating daily with the CPO. * Competitive Package: Receive highly competitive, investor-funded compensation within a fast-growing healthtech environment. * AI-First Culture: Work in an engineering culture that prioritizes output and velocity through AI-augmented workflows. * Career Growth: Benefit from clear advancement paths to Lead Shopify Engineer or Head of Frontend Engineering. * Flexible Location: Work from our Hamburg office or remotely from anywhere within Germany. DU BIST AM ZUG! Are you ready to join our team and actively shape the digital revolution in healthcare? Then we look forward to receiving your application!

suena energy

INTRO Hamburg Hybrid (2–3 days/week onsite) | 70.000 - 85.000 € p.a. (40 hrs / full time) | 30 Days Vacation | English B2 | German C1 Are you passionate about building the technical backbone of the energy transition? Join suena energy as Senior Backend Engineer (f/m/x) and become a founding member of our newly formed Platform team. You'll help design and build the API and integration layer that connects our trading, analytics, and optimization systems — and in doing so, directly shape how clean energy is managed across European power markets. suena energy is a green tech startup specializing in algorithmic energy trading for battery storage systems and renewables. Our vision: a world where clean energy is used reliably, economically, and intelligently. With our AI-based optimization and trading software, we maximize the revenues of operators of large-scale energy storage and renewable assets on short-term electricity and balancing markets - while simultaneously minimizing their risks. We're a team of 50+ people, combining a warm, supportive culture with real startup drive. Following our successful Series A, we're now building a dedicated Platform team from scratch. Quick Check: Is this your kind of engineering challenge? * Tech Stack: Python (Django/FastAPI), PostgreSQL/TimescaleDB, Redis, Celery, Docker, AWS, GitLab CI/CD, Sentry, Grafana * Your Focus: API design & architecture, backend integrations, data flows, system reliability and scalability * Team: Small, newly formed platform squad — you'll work closely with the Platform Lead, with strong support from our CTO in the early phase * Product: Real-time energy trading platform — high complexity, data-heavy, ML-integrated * Who thrives here: Engineers who think in systems, take ownership, and are energized by building things that actually matter * Must-haves: 5+ years backend experience, solid API & architecture background, Python, cloud deployment, German C1 * Dealbreakers: No API/architecture experience, pure CRUD background, no interest in complex distributed systems YOUR MISSION * Design and build scalable, reliable APIs and backend integrations that connect trading, analytics, data science, and forecasting systems * Drive the architecture of suena's platform layer — from initial design decisions to production * Own data flows and backend automations across the platform * Collaborate closely with the Platform Lead, CTO, and cross-functional teams (trading, data science, modelling) to translate complex domain requirements into robust technical solutions * Improve and extend existing systems while keeping a clear eye on reliability, security, and performance * Contribute to technical standards, code reviews, and engineering practices as the team grows YOUR PROFILE * 5+ years of backend engineering experience, with a strong focus on API design and system architecture * Solid Python skills (Django and/or FastAPI); hands-on experience with PostgreSQL/TimescaleDB is a plus * Experience with distributed/cloud-based architectures (AWS preferred), Docker, CI/CD, async workflows (Celery, Redis) * You think beyond the ticket — you understand how systems connect and can make principled architecture decisions * Security-minded: authentication, authorization, zero-downtime deployments are familiar territory * Comfortable working across greenfield projects and legacy systems * German C1 is required for this role — we work closely with German-speaking external API partners and system integrators, and clear, direct communication in German is essential for this * English B2/C1 for internal collaboration * Nice to have: Experience or genuine curiosity about energy markets, trading systems, or related domains (finance, IoT). The domain is complex — enthusiasm to learn it matters. WHY US? * Shape the Future: Contribute to the energy transition by working on sustainable energy solutions in a growing market environment. * Connecting & Co-Creating: Strategy off-sites and onsite weeks for real collaboration and shared ideas. * Work Your Way: Home office and flexible hours – you know what works best for you and your team. * Team Spirit: Yoga, shared lunches, after-work fun – we support each other and keep the vibe strong, even when it’s busy. * Fair & Transparent: Clear structures, democratic decisions, and a feedback culture where your voice counts. * Body & Mind: Urban Sports Club membership, wellbeing check-ins, and mental health support – your energy matters. * New Office Vibes: 10th-floor office with rooftop terrace, canteen, great views, ergonomic desks, hardware of your choice, and pet-friendly! * Sustainable Extras: Deutschlandticket, FutureBens, and more – supporting your mobility and future. WHAT ELSE? A note on applications As part of your application, we'd love to see a Python project you're genuinely proud of — production code, a side project, a study case, anything goes. It doesn't need to be polished. We'll use it as the basis for a technical conversation: what decisions did you make, why, what would you do differently? Send us the link of your repository. Be sure we have access. If you don't have something ready to share, no problem — we'll send you a small, focused task instead. Not quite senior level yet, but this role sounds like the direction you're heading? Apply anyway and let us know — we're also building out the junior side of the team. We look forward to receiving your application, earliest start is as soon as possible. If you have any questions, feel free to reach out - your contact is Kathi (Interim Talent Partner). You’ll hear back from us within 5 working days of your application. We value your time and want to make the process as transparent as possible. Once we receive your application, we’ll send you a confirmation email outlining the next steps and what you can expect from our interview process. We can’t wait to meet you! suena energy is an equal opportunity employer. We celebrate diversity and reject any form of discrimination. It is important to us to create an inclusive environment for all our team members. We want to particularly emphasize that our call for applicants is addressed to all genders. We welcome applications from people with disabilities.