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You will get Senior Full Stack Developer | React, Next.js & SaaS Specialist
Project details
Why work with me?
Proven Expertise: I've architected systems supporting 50K+ active users and processing 300K+ API requests monthly with 99.9% uptime.
Business-First Approach: I don't just follow tickets; I ensure the technology aligns with your ROI and user experience goals.
Full-Stack Mastery: Expert-level React, Next.js, and Node.js/Python integration for seamless end-to-end performance.
My 3-Step:
Strategic Discovery: We align your business requirements with a technical roadmap to ensure we build exactly what your users need.
High-End Engineering: Development of a clean, maintainable codebase using modern architecture (SSR, Microservices, or Scalable Monoliths).
Continuous Deployment: Setting up automated CI/CD, cloud infrastructure (GCP/AWS), and performance monitoring.
Tech Stack:
Frontend: React, Next.js, TypeScript, Tailwind.
Backend: Node.js, Express, Python (FastAPI), PostgreSQL, Redis.
Infrastructure: Docker, Google Cloud (GCP), Vercel, Git.
Let's turn your vision into a scalable reality. Send me a message to discuss your project before placing an order!
Proven Expertise: I've architected systems supporting 50K+ active users and processing 300K+ API requests monthly with 99.9% uptime.
Business-First Approach: I don't just follow tickets; I ensure the technology aligns with your ROI and user experience goals.
Full-Stack Mastery: Expert-level React, Next.js, and Node.js/Python integration for seamless end-to-end performance.
My 3-Step:
Strategic Discovery: We align your business requirements with a technical roadmap to ensure we build exactly what your users need.
High-End Engineering: Development of a clean, maintainable codebase using modern architecture (SSR, Microservices, or Scalable Monoliths).
Continuous Deployment: Setting up automated CI/CD, cloud infrastructure (GCP/AWS), and performance monitoring.
Tech Stack:
Frontend: React, Next.js, TypeScript, Tailwind.
Backend: Node.js, Express, Python (FastAPI), PostgreSQL, Redis.
Infrastructure: Docker, Google Cloud (GCP), Vercel, Git.
Let's turn your vision into a scalable reality. Send me a message to discuss your project before placing an order!
Programming Languages
HTML & CSS, JavaScript, TypeScriptCoding Expertise
Cross Browser & Device Compatibility, Performance Optimization, SecurityWhat's included $50
These options are included with the project scope.
$50
- Delivery Time 30 days
- Number of Revisions 0
- Design Customization
- Content Upload
- Responsive Design
- Source Code
Frequently asked questions
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MR
Maks R.
Aug 9, 2026
UX / Usability Testers (German-Based Only | 15-Min Microtask)
Herausragende Arbeit von Serhii! Schnelle Reaktionszeiten, extrem gründliches Testing und glasklares Feedback. Er hat meine Erwartungen weit übertroffen. Eine uneingeschränkte Empfehlung für jeden, der Top Ergebnisse sucht. Danke für die tolle Zusammenarbeit!
FR
Frank R.
Feb 14, 2025
Developer Needed to Build Custom Underwriting Portal for Loan Applications
About Serhii
Senior FullStack Engineer React/Node.js | Next.js/NestJS | AI-Native
44%
Job Success
Altena, Germany - 9:59 am local time
Hi, I am Serhii, an officially registered Freiberufler (independent contractor) based in Germany. I specialize in engineering robust web applications, startup MVPs, and complex SaaS solutions for businesses that value reliability, scalable architecture, and transparent processes.
Over the past 6+ years, I have successfully delivered multiple end-to-end projects, focusing on building systems that handle real production workloads—not just prototypes.
🔹 Workflow & Professional Standards
Local DACH Partner: Based in the Central European Timezone (CET), I provide seamless communication in English, German, and Russian. You get the legal and operational reliability of working with a Germany-based professional.
Transparent Processes: I strictly manage projects using Scrum and Jira methodologies, ensuring you have complete visibility into sprints, deliverables, and budget allocation.
AI-Native Efficiency: I leverage autonomous AI agents and modern tooling to accelerate code generation, conduct deep architectural analysis, and automate workflows, reducing your time-to-market.
Quality First: I do not compete on cheap labor; I compete on engineering excellence. My baseline for a simple landing page starts from €500, with custom SaaS platforms priced according to their architectural complexity.
🔹 Full Stack Web Development & SaaS
As a Full Stack Developer and React Node Full Stack Developer, I design comprehensive systems combining modern frontends with powerful backend services. I have extensive experience building SaaS platforms with complex billing logic (such as electronic invoicing for the German market) and AI-powered data management systems. My solutions are designed to scale, process heavy API traffic, and maintain exceptional uptime.
🔹 Frontend Development (React & Next.js)
For teams searching for a React Developer, Next.js Developer, or Frontend React Engineer: I build modern SPAs, SSR applications, and complex SaaS dashboards. Leveraging TypeScript, Next.js, and Tailwind CSS, I ensure pixel-perfect, responsive UIs. I am obsessed with frontend performance, consistently optimizing core web vitals to achieve "Perfect 100" Google Lighthouse scores.
🔹 Backend Development (Node.js/NestJS & Python)
As a Node.js Developer and Backend Engineer, I architect robust REST and GraphQL APIs using NestJS, Express, and Node.js. Furthermore, as a Python Developer, I build advanced data pipelines, backend automation, and AI integrations using Python and FastAPI.
🔹 Core Technologies & Roles I Fill:
Frontend: React Developer, Next.js Developer, Frontend Web Developer, Tailwind CSS, SPA, SSR.
Backend: Node.js Developer, NestJS, Express, Python Developer, FastAPI.
Database & Infrastructure: Prisma, PostgreSQL, MongoDB, Redis, Headless Architecture.
Methodologies: Scrum, Jira, Agile, RAG-based AI integration.
Whether you need a dedicated Frontend Engineer to perfect your UI or a Senior Full Stack Web Developer to architect your next SaaS platform from the ground up, I deliver maintainable, production-ready code.
📩 Click "Invite" or "Hire" to discuss your project architecture and business goals.
Steps for completing your project
After purchasing the project, send requirements so Serhii can start the project.
Delivery time starts when Serhii receives requirements from you.
Serhii works on your project following the steps below.
Revisions may occur after the delivery date.
Requirement Analysis & Technical Discovery
We will discuss your project goals, target audience, and specific feature requirements. I will review your wireframes or logic to ensure the technical stack (React/Next.js) is perfectly aligned with your business needs.
Architecture Setup & UI Prototyping
I set up the project environment, including the folder structure and core libraries. I build the primary layout and navigation of the dashboard to ensure the look and feel match your vision before diving into deep logic.