# REACTIVE STUDIO d.o.o.

> Product engineering partner for startups and growing companies. EU-based. We embed with your team and ship.

REACTIVE STUDIO is a founder-led software engineering studio based in Zagreb, Croatia. We work as an embedded engineering partner — joining teams directly, not as a vendor. We build mobile apps, integrate AI, ship fintech and crypto products, and handle complex backend systems.

## Services

- **Product Strategy & MVP Scoping**: Define the first useful version of a product. User flows, technical feasibility, launch priorities, and the tradeoffs that make or break an MVP. The goal is a product small enough to ship and useful enough to learn from.
- **Mobile App Development**: iOS and Android — native and cross-platform. Auth, payments, push notifications, BLE, analytics, CI/CD pipelines, App Store and Play Store releases. We've shipped apps that handle real transactions and real users at scale.
- **AI & Automation Integration**: LLM-powered copilots, workflow automation, RAG pipelines, agentic tools with human oversight. We integrate AI where it solves a real problem — not as a feature checkbox. Properly architected with guardrails, cost controls, and fallback paths.
- **Fintech, Crypto & Complex Systems**: Payment flows, wallet UX, on-chain integrations, KYC/AML constraints, multi-party settlement logic. When money moves or data is sensitive, the engineering has to be right.
- **Embedded Engineering**: We plug directly into your team — not as staff augmentation, but as engineers who own outcomes. Your tools, your rituals, your pace.

## How We Work

1. **Clarify** — Users, goals, constraints, risks. We align on what success looks like before touching any code.
2. **Shape** — Architecture, user flows, integrations, tradeoffs. Everything decided before development starts.
3. **Build** — Weekly builds you can see and test. Pragmatic decisions. Always moving toward a shippable release.
4. **Launch** — App store submission, deployment, monitoring, analytics. We handle the release and stay through go-live.
5. **Evolve** — After launch, we iterate based on real usage data and user feedback. The product gets better with every cycle.

## Experience

We have shipped products across multiple domains:

- **Fintech**: Mobile payment apps processing real transactions across EU markets. Payment gateway integrations, PSD2 compliance, real-time balance sync.
- **IoT & BLE**: Native mobile apps managing Bluetooth-connected hardware devices. OTA firmware updates, real-time sensor data, offline-first sync.
- **Crypto**: Wallet and portfolio experiences with on-chain transaction tracking, multi-chain support, and fiat on-ramp integration.
- **AI Integration**: LLM-powered workflow automation for internal operations teams. Document processing, structured extraction, human-in-the-loop review.
- **Startup MVPs**: End-to-end product builds for early-stage startups — from initial scoping through App Store launch. First users within 10 weeks.
- **Embedded Teams**: Multi-year engagements inside existing engineering teams, leading mobile product initiatives. Architecture decisions, code review, mentoring, feature delivery.

## Good Fit

- Founders and early-stage teams that need senior technical direction and execution to reach real users.
- Growing companies that need engineering capacity for a specific product push — mobile, AI, fintech — without hiring a full team permanently.
- Complex product challenges involving payments, hardware, blockchain, sensitive data, or AI — where engineering decisions carry real stakes.

## Technologies

iOS, Android, React Native, Flutter, Swift, Kotlin, Node.js, TypeScript, Python, Go, PostgreSQL, Firebase, AWS, GCP, REST APIs, GraphQL, Bluetooth Low Energy, Solana, Ethereum, OpenAI, Anthropic Claude, LangChain, vector databases.

## Company Details

- **Legal name**: REACTIVE STUDIO d.o.o.
- **OIB (Croatian tax ID)**: 68133057384
- **Registered office**: Radnička cesta 80, Zagreb, Croatia
- **Founder**: Alexander Štimac
- **Area served**: Worldwide (EU-based)
- **Contact**: info@reactive.studio
- **Website**: https://reactive.studio