Senior Fullstack Engineer

ABOUT US We’re Cortea, a Berlin startup transforming audits with AI. Manual, document-heavy audits waste expert time while demand keeps rising. Our AI-powered software and specialized AI agents remove the repetitive work so auditors can focus on judgment. Backed by top-tier VCs with >15m funding, with a working product and paying customers, we’re rapidly scaling. We value first-principles thinking, speed, trust, and kindness. We build side by side in our Berlin office. YOUR ROLE We're looking for an experienced engineer who's happy anywhere in the stack and turns complex audit workflows into product auditors rely on every day. You pick up whatever a problem needs, from the data model to the interface to the agents behind it. A lot of what we build has no reference implementation. You're comfortable wading into something nobody has solved yet and shipping a first version that actually works. Our engineering team is a small, flat group of builders: strong ICs who open a laptop when they see a problem instead of scheduling a meeting. Everyone owns real product and architecture decisions, and that's exactly what we want more of. WHAT YOU'LL DO * Build the interfaces auditors work in, partnering with design to turn complex flows into something that feels effortless * Build and improve the agents at the core of the product, plus the harnesses and eval pipelines around them * Make the long-running workflows behind the product reliable and debuggable, so failures surface fast instead of silently * Use AI heavily in your own workflow to move faster, without ever shipping output you can't stand behind * Drive the how in RFCs and technical discussions with other engineers, and partner with product on the what QUALIFICATIONS You'll fit here if you: * Have 5+ years shipping production web applications across the stack * Write production APIs and model the data behind them so it holds up under multi-tenancy and load * Are strong on the frontend and can build genuinely complex UI * Get how LLM agents actually work: agents, harnesses, tool use, and measuring quality with evals * Keep up with where AI is moving and bring the latest tools into how you work to make yourself faster * Bring a strong product mindset and real ownership of outcomes * Make architectural decisions, weigh trade-offs, and build things other engineers can extend * Are comfortable with ambiguity and work things out from fundamentals when there's no established answer Nice-to-haves that are a plus: * Hands-on experience building agents, harnesses, or eval pipelines * Data-dense or workflow-heavy B2B products * Scaling multi-tenant systems as data and traffic grow * Audit, finance, compliance, or another domain where being wrong is expensive * Early-stage startup or fast-moving engineering environment No one checks every box. If you ship across frontend, backend, and data and own what you build, let's talk. OUR TECH * React, TS, Tailwind, TanStack * Python, Postgres, Temporal, Kafka, Redis * GCP, Azure, k8s * GitHub, Linear, Slack, Notion WHAT WE OFFER * High impact & growth: Front-row seat to scaling an AI startup with real ownership from day one * Mission-driven culture: First-principles thinking, bold ideas, and a supportive team * Attractive compensation: competitive salary + meaningful equity * Personal development: Learning budget for courses and conferences * True Berlin startup environment: Central Berlin office, team lunches, retreats, flexible vacation INTERVIEW PROCESS * First Call — Intro to Cortea with our Founders Associate Liza * Second Call — Technical interview with our Member of Technical Staff Jendrik * Third Call — Deep dive into our culture with our Co-Founder Philipp * On-site Half-Day (Berlin) — Meet the team and work on a real problem together

OUR STORY: Every year millions of people are either filing their taxes in fear or giving up on their tax refund altogether. We're working on fixing that. Our intuitive app enables anyone, regardless of education or background, to file their taxes with newfound confidence. Spread across Germany, Spain and the UK, the team at Taxfix Group with its brands Taxfix and Steuerbot, is a compassionate group of solution-finders. We speak our minds openly, and with over 400 professionals, including tax experts, developers, and IT security experts. The group has facilitated more than 3.5 billion euros in tax refunds for its customers since its founding in 2016. YOUR CHALLENGE: As a Senior Software Engineer, you’ll build core features for our flagship product, turning complex tax scenarios into simple, reliable experiences. You’ll work in a cross‑functional team to ship delightful customer journeys, and you’ll champion a strong engineering culture that prioritises scalable design, quality, and maintainability. YOUR RESPONSIBILITIES AND DECISIONS: * Collaborating with product management and design to work towards help solve customer problems * Contribute to technical direction and strategy to further the long-term product vision. * Create a great developer experience through good tools and practices that empower seamless delivery. * Be part of cross-functional teams, working closely with other platform and product teams. * Collaborate with other engineers and support an environment that values development, growth, and a safe environment to raise challenges. YOUR PROFILE: * +5 years experience with React (ideally React Native) on the Frontend * +5 years of experience with node.js on Backend * Exposure to public Cloud Environment (Google Cloud, AWS or MS Azure) * Familiarity with DevOps tools and concepts * Familiarity with backend concepts and technologies (authentication systems, databases, cloud) * Experience with integrating with diverse APIs * Curiosity for AI-assisted development and familiarity with tools such as Cursor, GitHub Copilot or similar * Passionate about writing maintainable and elegant code. * A pragmatic person with a strong positive attitude. WHY TAXFIX? * A chance to do meaningful, people-centric work with an international team of passionate professionals. * Holistic well-being with free mental health coaching sessions and yoga. * A monthly allowance to spend on an extensive range of services that you can use and roll over as flexibly as you like. * Employee stock options for all employees—because everyone deserves to benefit from the success they help to create. * 30 annual vacation days and flexible working hours. * Work from abroad for up to six weeks every year. Just align with your team, and then enjoy your trip. * Plenty of opportunities to socialise as a team. In addition to internal tech meetups, our international team hosts regular get-togethers—virtually and in person when possible. * Free tax declaration filing, of course, through the Taxfix app—and internal support for all personal tax-related questions. * Have a four-legged friend in your life? We’re happy to have dogs join us in the office. Excited? So are we. Learn more about Team Taxfix on our blog and get a glimpse of our culture. At Taxfix, we believe that incredible things happen when you have a wealth of perspectives and experiences. We're proudly committed to equal employment and development opportunities no matter your gender, race, religion, age, sexual orientation, colour, disability, or place of origin. To help mitigate any potential unconscious biases, we ask that you refrain from including your picture, age, or marital status on your CV. Let your experiences speak for themselves. Not sure if you meet all the requirements for this role? Please apply anyway. You might bring something special to the team that we hadn't considered previously.