You will get Expert Bug Fixing, API Debugging, and MERN Optimization
Project details
A single hidden bug is like a leak in a structural beam—it might seem small, but it can bring down the entire system. Are you tired of 'temporary fixes' that break something else the next day?
I provide professional debugging and optimization services for your MERN stack applications. I don't just patch the holes; I perform a deep structural audit to find the root cause, ensuring your app remains stable, secure, and fast.
What i will solve:
1. Logic Errors: Fixing broken features and unexpected app behavior.
2. API & Integration Issues: Debugging failed requests and 3rd party API connections.
3. Auth & Security: Patching vulnerabilities and fixing login/signup flows.
4. Database Optimization: Resolving slow queries and data sync issues in MongoDB.
5. Deployment Errors: Fixing crashes on Vercel, Heroku, Digital Ocean Droplets or AWS.
I prioritize clean, maintainable code so that once a bug is fixed, it stays fixed.
I provide professional debugging and optimization services for your MERN stack applications. I don't just patch the holes; I perform a deep structural audit to find the root cause, ensuring your app remains stable, secure, and fast.
What i will solve:
1. Logic Errors: Fixing broken features and unexpected app behavior.
2. API & Integration Issues: Debugging failed requests and 3rd party API connections.
3. Auth & Security: Patching vulnerabilities and fixing login/signup flows.
4. Database Optimization: Resolving slow queries and data sync issues in MongoDB.
5. Deployment Errors: Fixing crashes on Vercel, Heroku, Digital Ocean Droplets or AWS.
I prioritize clean, maintainable code so that once a bug is fixed, it stays fixed.
Programming Languages
HTML & CSS, JavaScript, TypeScriptCoding Expertise
Performance Optimization, Security, DesignWhat's included
| Service Tiers |
Starter
$50
|
Standard
$150
|
Advanced
$200
|
|---|---|---|---|
| Delivery Time | 1 day | 3 days | 4 days |
Number of Revisions | 2 | 5 | Unlimited |
Bug Investigation | - | - | |
Fix Documentation | - | - | |
Detailed Code Comments | - | - |
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FV
Fannie V.
Jan 31, 2026
MERN Stack (NestJS) Developer Needed – Crypto Swap Bug Fix & Chat Module Implementation
Great experience working with Azhar. He fixed the swap module bug efficiently and implemented the chat module exactly as required. Very professional, good communication, and clean code. Highly recommended and happy to work together again.
About Azhar
Senior Full Stack Developer | MERN, Next.js & NestJS | Fintech & SaaS
50%
Job Success
Islamabad, Pakistan - 10:16 am local time
If you're building a product that needs to stay fast, secure, maintainable, and reliable under real production traffic, I focus on the engineering foundation that makes that possible.
At Extsy, a fintech crypto exchange, I built a React & Next.js trading dashboard and optimized backend performance with MongoDB indexing and Redis caching — reducing average API response time from 1.8s to 340ms while handling thousands of concurrent trading requests without downtime.
At Finzone, an ERP platform, I architected a modular full-stack codebase using NestJS and TypeScript, with a focus on clean architecture, maintainability, and long-term scalability.
What I can build and improve:
- Frontend & Web Applications
1. React.js & Next.js
2. TypeScript & JavaScript
3. Responsive, mobile-first web applications
4. Dashboards and complex user interfaces
- Backend & APIs
1. Node.js, Express.js & NestJS
2. REST API development
3. API integration and third-party integrations
4. Authentication, authorization, and secure backend systems
- Databases & Performance
1. MongoDB & PostgreSQL
2. Database architecture and query optimization
3. MongoDB indexing
4. Redis caching
5. API and application performance optimization
- SaaS & Production Systems
1. SaaS application development
2. Scalable web application architecture
3. Modular backend architecture
4. AWS, Docker, and CI/CD
5. Production deployment and ongoing optimization
I'm a Senior Full Stack Developer with 5 years of experience building crypto exchanges, ERP platforms, SaaS products, and other production web applications. I don't just make features work — I build systems that are easier to maintain, scale, and improve as the product grows.
If you need a React / Next.js frontend, Node.js / NestJS backend, REST API, SaaS application, or a complete full-stack web application, I can help take it from architecture and development through production deployment.
- FAQ
Q1: Can you handle both frontend and backend for my MVP?
Yes. I build end-to-end web applications using React, Next.js, Node.js, and NestJS, including REST APIs, databases, authentication, third-party integrations, and deployment.
Q2: Can you work on an existing application rather than building from scratch?
Yes. I can audit and improve existing codebases, fix bugs, optimize APIs and database queries, improve application performance, and refactor systems toward a more maintainable architecture.
Q3: What technologies do you primarily work with?
My core stack is React, Next.js, Node.js, NestJS, TypeScript, MongoDB, PostgreSQL, Redis, Docker, and AWS.
Q4: Can you build a scalable SaaS application?
Yes. I focus on modular architecture, clean APIs, database design, performance, security, and production deployment so the application has a solid foundation for future growth.
Q5: Do you provide post-launch support?
Yes. I provide a post-launch support window to address deployment issues, bugs, and initial production problems.
Steps for completing your project
After purchasing the project, send requirements so Azhar can start the project.
Delivery time starts when Azhar receives requirements from you.
Azhar works on your project following the steps below.
Revisions may occur after the delivery date.
Bug Diagnosis & Environment Setup
I will analyze the reported issue, reproduce the error in a local environment, and identify the root cause in the code or architecture.
Final Review & Delivery
I will provide a summary of the fix, share the updated code, and guide you on how to prevent similar issues in the future.