You will get I will fix bugs and improve performance in your React or Next.js app
Project details
I fix bugs and performance issues in React and Next.js apps — quickly and properly.
Senior Frontend Engineer with 5+ years of experience in SaaS and marketplace development. I focus on root-cause solutions, clean architecture, and long-term stability.
If your app feels slow, unstable, or messy — I can help fix it and make it reliable.
Senior Frontend Engineer with 5+ years of experience in SaaS and marketplace development. I focus on root-cause solutions, clean architecture, and long-term stability.
If your app feels slow, unstable, or messy — I can help fix it and make it reliable.
Programming Languages
HTML & CSS, JavaScript, TypeScriptCoding Expertise
Cross Browser & Device Compatibility, Performance Optimization, SecurityWhat's included
| Service Tiers |
Starter
$79
|
Standard
$199
|
Advanced
$399
|
|---|---|---|---|
| Delivery Time | 1 day | 2 days | 4 days |
Number of Revisions | 1 | 2 | 3 |
Number of Pages | 1 | 2 | 3 |
Design Customization | - | - | - |
Content Upload | - | - | - |
Responsive Design | - | ||
Source Code | - |
Optional add-ons
You can add these on the next page.
Code Review & Improvements
(+ 1 Day)
+$80
Performance Optimization
(+ 2 Days)
+$140Frequently asked questions
About Denys
Senior React / Next.js Engineer | TypeScript | Scalable SaaS & Web App
Hviezdoslavov, Slovakia - 1:04 pm local time
I specialize in React, Next.js, and TypeScript, focusing on performance, maintainable architecture, and excellent user experience.
In previous projects I helped companies:
• Improve search performance by **40%** in a large marketplace (30k+ products)
• Reduce API latency by **~20%** by improving frontend–backend interaction
• Increase application performance by **34%** through rendering optimization
• Reduce production bugs by **35%** using Playwright E2E testing
I work across the full stack when needed (Node.js, PostgreSQL, Prisma) but my main expertise is building robust, scalable frontends.
What I can help you with:
• React / Next.js development
• SaaS platforms and dashboards
• E-commerce systems
• Performance optimization
• Complex UI and data-heavy interfaces
• API integration and architecture improvements
Tech stack:
React • Next.js • TypeScript • Node.js • PostgreSQL • GraphQL • Prisma • Playwright • CI/CD • Vercel • AWS
I focus on clean architecture, performance, and delivering reliable production-ready software.
Let’s build something great together.
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.
Analyze the Issue
Review the provided details, reproduce the issue, and identify the root cause.
Plan the Solution
Define the best approach to fix the issue and improve stability or performance.