You will get fix Node.js, Next.js, React.js, MongoDB issues & optimize performance
Project details
🚀 Fix Node.js, Next.js, React.js & MongoDB Issues | Boost App Performance
Is your app crashing, loading slowly, or throwing unexpected errors? I’ll fix it fast and efficiently!
With over 8 years of experience, I specialize in debugging and optimizing web applications built with Node.js, Next.js, React.js, and MongoDB. Whether it’s backend issues, frontend bugs, database problems, or performance bottlenecks — I’ve got you covered.
🔧 Services I Offer:
Fix frontend/backend bugs
Debug API & database errors
Improve performance & load time
Refactor messy or inefficient code
Solve deployment/configuration issues
💡 Why Me?
Deep debugging expertise
Clean, maintainable code
Fast delivery with reliable results
Post-delivery support included
Perfect for fixing broken features, improving performance, and ensuring your app runs smoothly.
Let’s get your project back on track — message me to get started!
Is your app crashing, loading slowly, or throwing unexpected errors? I’ll fix it fast and efficiently!
With over 8 years of experience, I specialize in debugging and optimizing web applications built with Node.js, Next.js, React.js, and MongoDB. Whether it’s backend issues, frontend bugs, database problems, or performance bottlenecks — I’ve got you covered.
🔧 Services I Offer:
Fix frontend/backend bugs
Debug API & database errors
Improve performance & load time
Refactor messy or inefficient code
Solve deployment/configuration issues
💡 Why Me?
Deep debugging expertise
Clean, maintainable code
Fast delivery with reliable results
Post-delivery support included
Perfect for fixing broken features, improving performance, and ensuring your app runs smoothly.
Let’s get your project back on track — message me to get started!
Programming Languages
HTML & CSS, JavaScript, TypeScriptCoding Expertise
Cross Browser & Device Compatibility, Performance Optimization, SecurityWhat's included
| Service Tiers |
Starter
$40
|
Standard
$80
|
Advanced
$200
|
|---|---|---|---|
| Delivery Time | 1 day | 3 days | 5 days |
Number of Revisions | 3 | 5 | 7 |
Bug Investigation | |||
Fix Documentation | |||
Detailed Code Comments |
Optional add-ons
You can add these on the next page.
Fast Delivery
+$20 - $50
9 reviews
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FR
Flavio R.
Dec 4, 2025
Full-Stack TypeScript Developer for H-OS MVP
Mir Janar managed the project under a tight schedule. The delivered product matched our expectations nicely. He is resourceful and provided good adjustments to the structures. We are very satisfied with his work.
AM
Amr M.
Oct 6, 2020
Convert design into javascript/css/html page(React knowledge is preferred)
MS
Matthew S.
Sep 7, 2019
Seller profile work
Great experience working with Janar - would definitely contract him again!
AM
Amr M.
Aug 20, 2019
Senior React/Redux developer
He did good work with test project.
I wish you good luck in the future.
Thanks.
I wish you good luck in the future.
Thanks.
rl
reid l.
Aug 15, 2019
help fix some issues for my html site
thanks for the good work
About Mir Janar
Expert Full-Stack & Desktop Software Developer
Dhaka, Bangladesh - 10:36 pm local time
I specialize in full-stack development with Node.js and MongoDB, creating scalable, secure, and high-performance web applications. On the frontend, I work with React, Next.js, and TypeScript, while on desktop, I build cross-platform applications using Python and PySide6, including offline support and cloud sync.
I focus on building scalable, maintainable, and user-friendly software tailored to your business needs. Whether it’s a complex web platform, a desktop system, or an integrated solution, I can deliver robust, high-quality results efficiently.
Tech Stack & Expertise
(1) Web & Back-End Development :
(i) Node.js, Express.js, Next.js, Python, FastAPI, Django, n8n
(ii) GraphQL & REST API design
(iii) MongoDB, PostgreSQL, SQLite
(2) Desktop Development :
(i) Python + PySide6 (Qt for modern, responsive UIs)
(ii) SQLite (local storage) + Cloud/MongoDB sync
(iii) Cross-platform apps (Windows/Linux)
(3) Front-End Development :
(i) React, Next.js (App Router, Server Actions)
(ii) Redux Toolkit, Zustand
(iii) TypeScript, JavaScript (ES6+)
(4) UI/UX & Design :
(i) Tailwind CSS, ShadCN UI, Bootstrap, Sass/Less
(ii) Framer Motion (animations)
(iii) D3.js & Chart.js (data visualization)
(5) Other Skills :
(i) Real-time apps (WebSockets / Socket.IO)
(ii) PWA (offline sync, push notifications)
(iii) Cloud Hosting
(iv) Git/GitHub/GitLab
Why Work With Me?
(i) 8+ years of delivering scalable, maintainable solutions
(ii) Expertise in both cloud-native web apps & desktop software
(iii) Strong focus on clean architecture, performance, and user experience
(iv) Flexible: can adapt to any stack or project requirement
Long-term mindset — I focus on building solutions that grow with your business
If you need a skilled developer who can handle everything from UI to backend logic to desktop apps, I’m here to help.
Steps for completing your project
After purchasing the project, send requirements so Mir Janar can start the project.
Delivery time starts when Mir Janar receives requirements from you.
Mir Janar works on your project following the steps below.
Revisions may occur after the delivery date.
Requirement Gathering
You share the issue details, app behavior, and access to the code or repo (GitHub, ZIP, etc.).
Issue Analysis & Debugging
I analyze logs, reproduce the problem, and identify the root cause using debugging tools and experience.