Senior Full Stack Developer React/FastAPI/Django (Frontend-Affinity) (m/f/d)

mika is revolutionizing financial management for small businesses with an AI-powered platform that combines automated accounting, proactive insights, and conversational AI. We're on a mission to make expert financial navigation and compliance accessible to every small business owner – dramatically reducing costs and bureaucratic burden. We're a small, senior team shipping fast, and every line of code we ship matters.
Our stack: FastAPI & Django backend, React frontend (Material UI, react-query), PostgreSQL, AWS. We build agentic AI systems that do real accounting work.
Tasks
We need a Senior Full-Stack Developer who leans frontend – someone who makes our product _look and feel_ as good as it works under the hood.
You'll own features end-to-end. That means you think through the entire user flow, edge cases, error states, and architecture _before_ you start building. You work with high autonomy and take real ownership – we trust you to make good decisions and deliver clean solutions.
Concretely, you'll:
* Drive frontend improvements – not just fixing bugs but proactively elevating UX and visual quality on a regular cadence
* Build and own complex full-stack features in our accounting platform
* Use Claude Code, Cursor, or similar AI engineering tools as your primary development workflow – we are a senior team where everyone writes high-quality code at a high pace, and this is only possible through the use of the latest coding tools. You'll get access to all the subscriptions you need to work efficiently
* Adapt and extend our Python/FastAPI & Django backend where needed (CRUD-level changes and beyond)
* Contribute to code quality and architecture decisions in a small senior team
Requirements
* Professional experience in software development with a proven track record of owning and delivering complex projects.
* Expertise in React to build high-quality, accessible, and production-ready user interfaces.
* A sharp eye for design that ensures layouts and components are implemented with pixel-perfect accuracy.
* Hands-on skill with AI-assisted engineering using tools like Cursor, Claude Code, Codex, or GitHub Copilot. You have already built real things with those tools.
* The ability to work across the stack by independently navigating and extending a Python/FastAPI backend.
* A systems-thinking mindset to map out full features, edge cases, and failure modes before writing any code.
* Fluency in English, while any knowledge of German is a welcome bonus.
Nice to have:
* Background in agentic AI systems or LLM-powered products.
* Familiarity with B2B fintech, PostgreSQL, or German accounting standards like DATEV.
Benefits
* A small team of strong, senior engineers who respect each other's time.
* Real autonomy and ownership from day one.
* Work that's genuinely hard and interesting – German tax law + AI agents is not a solved problem.
* Competitive salary and a product that's actually used by real customers daily.
* Almost no meetings – on average 95% focus time per day.
* 100% Remote option, option to work abroad and no minimum required office attendence.
* Fully flexible working hours apart from Daily Standup.
* Berlin location preferred but remote possible.
_We welcome applications from people of all backgrounds, genders, and identities._