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.

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