Fix / Refactor / Scale Your Existing AppSergii Kirianov
Most apps slow down or break because they were built fast, without clear technical ownership. I help founders fix and stabilize existing Next.js, React Native, and Node.js applications so they can grow without firefighting.
I start with a deep audit of your architecture, performance, and database. Then I fix critical issues, refactor messy code, improve load times, stabilize deployment pipelines, and create a clean, maintainable foundation your team can build on.
This service is ideal for teams whose product works…but not reliably. You’re getting a senior engineer who has scaled real systems to thousands of daily users and knows how to rescue struggling codebases the right way.
What's included
Architecture Review
A deep dive into your current codebase: structure, dependencies, bottlenecks, tech debt, and scaling risks.
Fix Critical Issues & Crashes
Resolve bugs, runtime errors, broken flows, deployment problems, and unstable features.
Performance Optimization
Improve load times, memory usage, API efficiency, and overall responsiveness across web or mobile.
Code Cleanup & Refactor
Rewrite messy logic, simplify components, improve readability, and align your app with best practices.
Database Optimization
Fix slow queries, improve indexing, clean schema issues, and enhance reliability (SQL Databases).
DevOps & Deployment Improvements
Stabilize hosting (Vercel/Docker), fix CI/CD issues, clean environment setups, and improve reliability.
Clear Improvement Report
A final breakdown of what was fixed, refactored, or improved — with future recommendations.
FAQs
Yes, for meaningful fixes. I can sign an NDA, and all work happens through private branches and PRs.
That’s exactly the point of this service. I specialize in rescuing messy or rushed codebases and turning them into stable, maintainable systems.
A lot. Most founders see major improvements in the first 3–5 days: crashes resolved, performance doubled, deployments fixed, and core flows stabilized.
Yes. I’ve cleaned up legacy React apps, outdated Node APIs, messy monorepos, and supersized Next.js projects many times.
Yes. Every engagement ends with a clear, written summary: issues found, fixes applied, and suggestions going forward.
Absolutely. Many clients move into ongoing retainers for continued development, scaling, and technical leadership.
Example work
Starting at$80 /hr
Tags
Node.js
PostgreSQL
React
React Native
TypeScript
Fullstack Engineer
Software Architect
Web Developer
Service provided by
Sergii Kirianov proCalgary, Canada
- 3
- Followers
Fix / Refactor / Scale Your Existing AppSergii Kirianov
Starting at$80 /hr
Tags
Node.js
PostgreSQL
React
React Native
TypeScript
Fullstack Engineer
Software Architect
Web Developer
Most apps slow down or break because they were built fast, without clear technical ownership. I help founders fix and stabilize existing Next.js, React Native, and Node.js applications so they can grow without firefighting.
I start with a deep audit of your architecture, performance, and database. Then I fix critical issues, refactor messy code, improve load times, stabilize deployment pipelines, and create a clean, maintainable foundation your team can build on.
This service is ideal for teams whose product works…but not reliably. You’re getting a senior engineer who has scaled real systems to thousands of daily users and knows how to rescue struggling codebases the right way.
What's included
Architecture Review
A deep dive into your current codebase: structure, dependencies, bottlenecks, tech debt, and scaling risks.
Fix Critical Issues & Crashes
Resolve bugs, runtime errors, broken flows, deployment problems, and unstable features.
Performance Optimization
Improve load times, memory usage, API efficiency, and overall responsiveness across web or mobile.
Code Cleanup & Refactor
Rewrite messy logic, simplify components, improve readability, and align your app with best practices.
Database Optimization
Fix slow queries, improve indexing, clean schema issues, and enhance reliability (SQL Databases).
DevOps & Deployment Improvements
Stabilize hosting (Vercel/Docker), fix CI/CD issues, clean environment setups, and improve reliability.
Clear Improvement Report
A final breakdown of what was fixed, refactored, or improved — with future recommendations.
FAQs
Yes, for meaningful fixes. I can sign an NDA, and all work happens through private branches and PRs.
That’s exactly the point of this service. I specialize in rescuing messy or rushed codebases and turning them into stable, maintainable systems.
A lot. Most founders see major improvements in the first 3–5 days: crashes resolved, performance doubled, deployments fixed, and core flows stabilized.
Yes. I’ve cleaned up legacy React apps, outdated Node APIs, messy monorepos, and supersized Next.js projects many times.
Yes. Every engagement ends with a clear, written summary: issues found, fixes applied, and suggestions going forward.
Absolutely. Many clients move into ongoing retainers for continued development, scaling, and technical leadership.
Example work
$80 /hr