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You will get Full backend development for apps

Denys K.Status: Offline
Denys K. Denys K.
5.0
Top Rated
Preview image

Let a pro handle the details

Buy Web Application Programming services from Denys, priced and ready to go.
Denys K.Status: Offline
Denys K. Denys K.
5.0
Top Rated
Preview image

Let a pro handle the details

Buy Web Application Programming services from Denys, priced and ready to go.

Project details

Are you building a mobile or web application and need a reliable backend that can handle real users and real traffic? ⚙️

A strong backend is not just endpoints - it’s structured architecture, clean data models, and stable deployment pipelines.

Whether you’re launching an MVP or rebuilding an existing system, I deliver backend solutions built for stability and long-term scale.

Message me before placing an order to align on your product requirements and technical goals.

Buzz: full backend development for apps, app backend development, backend development for mobile apps, backend development for web apps, full app backend development service, scalable app backend development, backend architecture development for apps, backend api development for apps, mobile app backend development expert, backend infrastructure for applications, backend system development for apps, backend engineering for applications, backend development service for apps, backend platform development for apps, backend development for saas apps, backend development consulting for apps, secure backend development for applications, production ready app backend development, backend development expert for apps
Programming Languages
JavaScript, Python, TypeScript
Coding Expertise
Localization, Performance Optimization, Security
What's included
Service Tiers Starter
$50
Standard
$100
Advanced
$200
Delivery Time 14 days 30 days 60 days
Number of Revisions
012
Number of Pages
555
Design Customization
-
-
Content Upload
Responsive Design
Source Code
-
5.0
1 review
100% Complete
(1)
1% Complete
(0)
1% Complete
(0)
1% Complete
(0)
1% Complete
(0)

AR

Alexander R.
5.00
Mar 13, 2026
AI developer/team with React Native and Python experience for the Babycare/Wellness APP Denys worked on our Mobile Application as a Full Stack developer using React Native and Python. He helped with mobile features, backend logic, and AI-related functionality. Communication was clear, tasks were delivered on time, and he focused on practical solutions that improved app stability and performance. It was a pleasure working with Denys.
Denys K.Status: Offline

About Denys

Denys K.Status: Offline
Full Stack Developer | Mobile App Development | SaaS Developer
100% Job Success
5.0  (1 review)
Odesa, Ukraine - 5:11 am local time
Most products do not fail because of bad code - they fail because nobody thought about architecture before writing it. As a Top Rated Plus Full Stack Developer and Mobile App Developer with a 100% Job Success Score on Upwork, I bring that thinking to every project, from MVP to production scale.

I'm a Full Stack Developer, Mobile App Developer, and Backend Developer focused on production-ready software that holds up under real-world usage. My work sits at the intersection of Software Developer, Senior Web Developer, and SaaS Development specialist, with a backend-first mindset and deep attention to scalability and maintainability - from React Native and Flutter on mobile to Python, Node.js, and Laravel on the backend. As a Full Stack Developer and Backend Developer, I own every layer, from React components to AWS architecture.

Core Specializations

Full Stack Web & API Development
As a Web Developer and React Developer comfortable across the entire stack, I build end-to-end solutions using React, Vue, Next.js, and TypeScript on the frontend, paired with Python (FastAPI, Django, Flask), Node.js, and Laravel on the backend. As a Front End Developer handling Web Design and component architecture, while I have previously worked as a Wordpress developer, my current focus is on custom SaaS Development and API-driven systems. As a Full Stack Developer, I own delivery from database schema to deployed product.

Scalable Backend Architecture
As a Python Developer and Node.js specialist, I build robust APIs for high concurrency - including SaaS Developer products that require multi-tenant architecture and subscription logic. As a Backend Developer, I focus on stable systems - REST or GraphQL - that handle complex business logic without performance degradation. As a DevOps-minded Full Stack Developer, I manage deployment pipelines and infrastructure as code across AWS and Microsoft Azure environments.

Performance Optimization & Systems Recovery
As a Full Stack Developer specializing in Mobile App Developer work, I resolve critical bottlenecks across mobile and web - reducing React Native app startup times, fixing memory leaks in Flutter apps, and resolving crashes in Swift and Kotlin codebases. Whether working as an Android Developer or iOS Developer, this is where my depth as a Mobile App Developer makes a difference in retention.

AI-Integrated Mobile App Developer Work
As a Full Stack Developer focused on Mobile App Developer work, I deliver intelligent cross-platform mobile apps as a React Native Developer and Flutter Developer, with native experience in Swift and Kotlin. I integrate OpenAI API, LangChain, and RAG systems for AI and API Integration that feels native and responsive on both iOS and Android, covering the full lifecycle from design and testing to App Store and Play Store deployment.

Data & Cloud Infrastructure
As a Full Stack Developer and AWS Architect, I bring deep expertise in AWS (Lambda, S3, DynamoDB), Microsoft Azure, PostgreSQL, and Redis. As a DevOps-focused engineer, I protect sensitive user data across Web, Android, and iOS platforms.

When projects require AI-powered functionality, I bring hands-on experience integrating AI into backend and mobile systems alike. This allows me, as a SaaS Developer, to deliver AI Integration that is reliable, observable, and cost-controlled rather than experimental.

Clients typically work with me when they need:
- a Full Stack Developer who can own frontend and backend
- a Mobile App Developer with React Native, Flutter, and native iOS/Android experience
- a Senior Web Developer or Backend Developer experienced with real production systems
- AI Integration and API Integration for existing or new platforms
- a SaaS Developer who understands long-term scalability constraints
- AWS Architect or Azure-based cloud infrastructure
- MVPs that can realistically evolve into long-term SaaS Development products

Technical Expertise
- Mobile: React Native, Flutter, Swift, Kotlin, TypeScript, Redux Toolkit, React Query
- Frontend: React, Vue, Next.js, TypeScript, Tailwind CSS
- Backend: Python (FastAPI, Django, Flask), Node.js, Laravel, PHP, REST & GraphQL
- AI & Automation: OpenAI API, LangChain, Vector Databases, RAG, AI Machine Learning
- Data & Cloud: AWS (S3, Lambda, DynamoDB), Microsoft Azure, PostgreSQL, Redis
- Tools: Docker, CI/CD, Git, Stripe, DevOps pipelines

Professional Approach

Having worked across Wellness, Fintech, Healthcare, and SaaS Development as a Full Stack Developer and Mobile App Developer, I provide architecture that scales, transparent communication, and end-to-end delivery from database schema to cloud deployment on AWS and Azure.

I do not take on Wordpress developer projects, SaaS marketing, Google Ads, or Digital Marketing services.

If you need a Full Stack Developer or Mobile App Developer to own the roadmap from MVP to production scale - let us discuss your project on Upwork.

Steps for completing your project

After purchasing the project, send requirements so Denys can start the project.

Delivery time starts when Denys receives requirements from you.

Denys works on your project following the steps below.

Revisions may occur after the delivery date.

Discovery & Requirements Review

Client shares project details, goals, scope, and any existing materials. I review everything and align on expectations, timeline, and deliverables.

Review & Revisions

Client reviews the work. I apply agreed revisions and fine-tune the final output.

Review the work, release payment, and leave feedback to Denys.