React Experts in Berlin

Stefan O.

AI Product Leader

Last position:

Founder at ProtocolEngine.io

Evidence-led health intelligence platform turning published research into personal health protocols. It scores 430 habits, foods, and supplements against the studies behind them, and moves the score when the evidence moves. Built solo.

Built the daily ingestion pipeline across PubMed, bioRxiv, and medRxiv: 43,000+ papers from 3,400+ journals processed into 230,000+ typed evidence claims, each one traceable back to the study it came from.
Designed the six-factor evidence scoring model and the public changelog behind it, so no recommendation ever appears without the papers underneath it. 23,000+ grade changes recorded and explained to date.
Shipped an entity information model connecting every intervention to its mechanisms, biomarkers, and outcomes: 118 biomarkers with region-specific reference ranges, 77 mechanisms, 32 graded outcomes.
Built the personalisation layer: blood panel ingestion that reads lab PDFs with a vision model and corrects results for draw time against the user's wake anchor, plus Oura, WHOOP, and Withings integration for daily readiness context.
Operate eleven specialised review agents over the corpus and codebase, covering paper curation, retrieval quality, health-claim compliance across EU and US regimes, and security.
Shipped the Evidence Assistant, a RAG assistant that answers from the claim database and cites the underlying papers, plus a B2B practitioner tier, an Expo React Native app, and localisation across 3 languages and 7 markets.

Stack: Next.js 16, TypeScript, Supabase, pgvector, Anthropic Claude, Vercel, DeepInfra.

Sascha B.

Frontend / UX Engineer

Last position:

Web Developer at GxPlex

Built a customized MediaWiki instance, including installation, MySQL database, SSL, and automatic backups
Set up user roles (Admin, Mod, Verified, User) and a permissions system
FlaggedRevisions for editorial review workflows · Commenting and rating extensions

Chintan P.

Product Owner and Technical Product Lead

Last position:

Product Owner and Technical Product Lead at Sustamize GmbH

LLM-based features for automated CO₂e data extraction from unstructured documents (70% reduction)
Agentic AI pipeline for automated Scope 3 emissions calculations with 150.000+ validated data records
Intelligent API workflows for real-time carbon footprint calculations in ERP and ESG systems
ML algorithms for predicting emissions hotspots and optimizing product design
Automated data validation pipelines with NLP for quality assurance of CO₂e datasets
Led a 15-person cross-functional team in developing 10+ AI features
Strategic product planning and AI roadmap with 35% shorter time-to-market
Stakeholder management with DAX companies (40% higher satisfaction, 95% retention)
On-time project delivery with 95% budget adherence through data-driven backlog management
Agile methods (Scrum, Kanban) with continuous AI/ML integration (25% increase in team velocity)
Product-market fit for AI features through A/B testing and analytics (60% higher adoption rate)

Ines S.

UX/UI Designer

Last position:

Freelance UX Designer at Ines Siebrecht UX | UI Design

Oleg A.

Staff Software Engineer

Last position:

Staff Software Engineer at Kpler Germany GmbH

Delivered a new notifications platform implementation built from scratch to replace existing and upcoming services
Collaborating with other teams to integrate more domains

Tech stack:

Data: Scala 3, Apache Kafka, Python, Airflow, Astronomer
BE-FE: TypeScript, NestJS, Java, Spring Boot, Vue
Dev-ops: AWS, PostgreSQL, Docker, GitHub Actions, Kubernetes, Helm, ArgoCD

Alexandr K.

Principal Engineering Consultant

Last position:

Technical Co-Founder at Dealyv

Joined the initial development team and helped transform an n8n prototype into a production-ready 0-to-1 product in a fast-paced environment.
Owned delivery across CRM and Twilio integrations, customer communication workflows, and administrative interfaces.
Collaborated on AI evaluation, microservice architecture, and other cross-functional product and engineering topics.
Supported the CEO across VC communications, customer acquisition, product positioning, onboarding, documentation, pricing, and sales.

Mukund B.

Last position:

Voice AI Chatbot - Real-Time Audio Assistant

▶ Built real-time voice assistant (STT → LLM → TTS pipeline) benchmarking and evaluating multiple STT providers including faster-whisper and Azure Speech. achieved sub-3s latency, Groq API (Llama 3) with multi-turn memory - directly handling edge cases in dictation, names and passcode recognition.

Anna M.

Senior JavaScript Engineer - TypeScript, Frontend Architecture & Developer Experience

Last position:

Freelance Frontend Consultant at Mister Spex

Developed complex React/TypeScript frontend systems for highly customizable lens products.
Designed internal tooling for validating and managing product configuration constraints.
Led accessibility initiatives to align customer-facing applications with EU accessibility requirements.
Worked extensively in large legacy codebases while incrementally improving maintainability and developer experience.
Collaborated across multiple teams in an international e-commerce environment.

Rüdiger S.

Full-Stack Software Engineer / Consultant for Digitalization

Last position:

Full-Stack Software Engineer / Consultant for Digitalization at ARTEVENT

Designed, built, and launched an internal event planning web application used by over 100 department leads for a large event, despite having no dedicated testing phase.
Ensured smooth, failure-free operation during first production use, leading to the tool being adopted for future events.
Automated catering calculations and related workflows, significantly reducing email communication and manual computation effort for meal planning.
Managed deployment and hosting on a Linux server using Coolify, including application setup and runtime operations.
Hired and guided a communication designer on UX while independently owning all technical decisions and implementation.

Marvin M.

AI Engineer & Architect · LLM and Multi-Agent Systems

Last position:

Co-founder & CTO · Freelance Software Engineer (AI & SaaS) at Self-employed

Self-employed · Berlin, Germany
Co-founded the company and own the entire technical side: product architecture, backend, frontend, infrastructure and operations.
Designed and built the Automated Booking System (ABS) as well as the core platform and payment logic.
Development of AI-powered SaaS products, from architecture through backend and frontend to production operation.
Technical consulting on product architecture, data protection and permissible automation.
Building, running and monetising my own API products for AI agents, each available as a REST interface and as an MCP server.
Full ownership of architecture, infrastructure, billing, legal texts and go-to-market.

Aruldass A.

Full-stack AI Engineer

Last position:

Web Module Lead at Mphasis Limited

Led the end-to-end delivery of enterprise full-stack web applications by driving requirement analysis, solution design, frontend and backend development, database design, API integration, code reviews, team coordination, Agile execution, CI/CD deployments, production support, performance optimization, security implementation, and stakeholder collaboration to deliver scalable, high-quality software solutions.

Jorge N.

Senior AI Engineer | Backend Developer C#/.NET | RAG, LLM Integration, Semantic Kernel | Azure, GCP, AWS

Last position:

Senior Developer at SafeXSmart KI Solutions UG

AI Platform Backend – Senior Developer

Brought in to design and build a backend for an AI platform from scratch, including multi-provider LLM orchestration and real-time infrastructure for AI influencer personas at scale.

Tasks and responsibilities

Architecture and implementation of a multi-LLM orchestration layer with Semantic Kernel to integrate GPT-4 and other providers for core platform logic and AI influencer personas, reducing model-switching overhead by abstracting provider APIs behind a single interface.
Design and development of a backend from scratch in C# / .NET 10, including domain modeling with DDD, a versioned RESTful API layer, and cloud infrastructure setup on Azure.
Built a real-time chat infrastructure with Server-Sent Events (SSE), message persistence, and delivery guarantees for live operation of AI influencer personas at scale.
Developed a media management service with integration of cloud object storage for upload and retrieval of influencer-generated content.
Created an integration and unit test suite with data seeding for reliable regression testing across all core platform flows, significantly reducing production error rates.

Tools and technologies: C#, .NET, ASP.NET Core, Python, TypeScript, MySQL, Semantic Kernel, EF Core, Minimal APIs, LLM Orchestration, Prompt Engineering, Agentic AI, Generative AI, AI-Assisted Engineering, Claude Code, GitHub Copilot, Google Gemini, OpenAI API, Ollama, Redis, Azure, Azure Container Apps, Azure Database for MySQL, Docker, GitHub Actions, Clean Architecture, Vertical Slice Architecture, CQRS, Domain-Driven Design, REST API, xUnit, Integration Testing, Unit Testing, Jira, Confluence, Scrum

Murad H.

Senior Software Engineer · Tech Lead · AI Engineer

Last position:

Founder & Technical Lead at Hubpoint.Ai

Founded an AI-powered scheduling and business-management SaaS for SMBs, owning technology strategy, architecture, product development, UX, billing and go-to-market execution.
Architected and shipped a multi-tenant platform with REST APIs, RBAC, CRM, billing and notifications, powering the manager dashboard, admin console, booking experience and iOS/Android applications.
Led and mentored 7 software engineers, 1 DevOps engineer, 1 QA engineer and 1 UX/UI designer, while remaining hands-on across backend, frontend and product delivery.
Built AI voice and chat agents using Python/FastAPI, OpenAI and Anthropic APIs, RAG, pgvector and tool calling; integrated Twilio, Google Calendar/Meet, Stripe and Firebase.
Owned production infrastructure and automated delivery across separate environments using Docker, Nginx, GitHub Actions and Grafana; represented the company at accelerators and international startup events.

Selected stack: Python, FastAPI, Node.js, Vue 3, React/Next.js, React Native, PostgreSQL, Redis, Docker

Santhosh K.

Freelance Software Engineer

Last position:

Freelance Software Engineer at Zalando SE

Drive migration of enterprise authorization platform from Styra DAS to open-source OPA via Skipper (Zalando's Golang-based ingress proxy) integration
Optimise k8s resources and integrate native Prometheus metrics with OPA
Migrate from internal monitoring solution to Prometheus CRs + Dash0

Tech Stack: Java/Kotlin, Golang, Python, Spring Boot, AWS, Kubernetes, Docker, OpenTofu, Prometheus, Grafana

Maciej R.

Full Stack Developer