You will get Fix JavaScript or TypeScript Bugs Fast — Production-Ready Patches
Project details
Is a bug blocking your release? Crashing your users? Silent and impossible to reproduce?
I'm a Senior Full-Stack Developer with 5+ years of experience in production JS/TS codebases
— from small SaaS apps to enterprise platforms used by thousands.
I fix:
✦ Runtime errors & unhandled promise rejections
✦ Type errors, strict-mode TS mismatches, and "any" abuse
✦ Logic bugs hiding behind async/await or Promises
✦ Memory leaks (closures, event listeners, intervals)
✦ Broken third-party integrations (APIs, SDKs, libraries)
✦ Edge-case failures that only appear in production
Every patch includes:
→ Root-cause explanation (not just a quick patch)
→ A before/after diff you can review and understand
→ Guidance on how to avoid the same bug in the future
I work with vanilla JS, TypeScript, React, Vue, Node.js, Next.js, and most modern frameworks.
No black-box fixes. No "it works on my machine."
I'm a Senior Full-Stack Developer with 5+ years of experience in production JS/TS codebases
— from small SaaS apps to enterprise platforms used by thousands.
I fix:
✦ Runtime errors & unhandled promise rejections
✦ Type errors, strict-mode TS mismatches, and "any" abuse
✦ Logic bugs hiding behind async/await or Promises
✦ Memory leaks (closures, event listeners, intervals)
✦ Broken third-party integrations (APIs, SDKs, libraries)
✦ Edge-case failures that only appear in production
Every patch includes:
→ Root-cause explanation (not just a quick patch)
→ A before/after diff you can review and understand
→ Guidance on how to avoid the same bug in the future
I work with vanilla JS, TypeScript, React, Vue, Node.js, Next.js, and most modern frameworks.
No black-box fixes. No "it works on my machine."
Programming Languages
JavaScript, TypeScriptWhat's included
| Service Tiers |
Starter
$80
|
Standard
$160
|
Advanced
$280
|
|---|---|---|---|
| Delivery Time | 1 day | 3 days | 5 days |
Number of Revisions | 1 | 2 | 3 |
Bug Investigation | |||
Fix Documentation | - | - | - |
Detailed Code Comments |
Optional add-ons
You can add these on the next page.
write a unit test
(+ 1 Day)
+$40Frequently asked questions
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WS
Wassim S.
Jul 4, 2026
fix a bug in my web site
Great experience working with Marwen. He delivered fast, communicated clearly throughout, and kept me updated at every step. Quick to understand what I needed and easy to work with would definitely hire again
About Marwen
Senior Full Stack React Node.js Three.js React Native
Lisbon, Portugal - 3:36 am local time
Web · Mobile · 3D · Performance · Security
Freelance, B2B & contract — DM or email to get started.
Steps for completing your project
After purchasing the project, send requirements so Marwen can start the project.
Delivery time starts when Marwen receives requirements from you.
Marwen works on your project following the steps below.
Revisions may occur after the delivery date.
Bug Diagnosis & Root-Cause Analysis
I set up the environment, reproduce the error, and pinpoint exactly where and why the code is failing
Developing & Testing the Fix
I write a clean, production-ready patch to fix the issue. I test it locally against edge cases and, if applicable