You will get MERN Full-Stack Bug Fixing, Cleanup & Optimization | React/Node, TypeScript
Rising Talent
Project details
🐞 MERN + TypeScript Full-Stack Bug Fixing, Code Cleanup & Performance Optimization
Is your MERN application running into bugs, slow performance, broken features, or messy code? I specialize in stabilizing and optimizing MERN + TypeScript projects so your app runs smoothly, securely, and efficiently.
What I Fix & Improve:
• Frontend bugs (React.js, TypeScript, Redux, UI issues, state errors)
• Backend issues (Node.js, Express, TypeScript, APIs, routing, middleware)
• MongoDB errors, slow queries & schema improvements
• App crashes, console errors, typing errors & inconsistent behaviors
• Authentication, JWT, sessions & role permissions
• API integration errors (REST, Axios, Fetch)
• UI/UX inconsistencies & responsive layout fixes
• Code cleanup, refactoring & TypeScript best practices
• Performance optimization (frontend + backend)
Tech Stack:
MongoDB, Express, React, Node.js, TypeScript, Redux, Tailwind, REST APIs, Git
Why Work With Me?
✔ Fast, accurate diagnosis
✔ Clean, maintainable fixes
✔ Strong TypeScript expertise
✔ Transparent communication
Need expert debugging or optimization? Send me your issue details and I’ll get it running perfectly!
Is your MERN application running into bugs, slow performance, broken features, or messy code? I specialize in stabilizing and optimizing MERN + TypeScript projects so your app runs smoothly, securely, and efficiently.
What I Fix & Improve:
• Frontend bugs (React.js, TypeScript, Redux, UI issues, state errors)
• Backend issues (Node.js, Express, TypeScript, APIs, routing, middleware)
• MongoDB errors, slow queries & schema improvements
• App crashes, console errors, typing errors & inconsistent behaviors
• Authentication, JWT, sessions & role permissions
• API integration errors (REST, Axios, Fetch)
• UI/UX inconsistencies & responsive layout fixes
• Code cleanup, refactoring & TypeScript best practices
• Performance optimization (frontend + backend)
Tech Stack:
MongoDB, Express, React, Node.js, TypeScript, Redux, Tailwind, REST APIs, Git
Why Work With Me?
✔ Fast, accurate diagnosis
✔ Clean, maintainable fixes
✔ Strong TypeScript expertise
✔ Transparent communication
Need expert debugging or optimization? Send me your issue details and I’ll get it running perfectly!
Programming Languages
PHP, JavaScript, TypeScriptCoding Expertise
PSD to HTML, Performance Optimization, W3C Markup Validation ServiceWhat's included $95
These options are included with the project scope.
$95
- Delivery Time 3 days
- Number of Revisions 1
- Bug Investigation
- Fix Documentation
- Detailed Code Comments
4 reviews
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JA
Joann A.
Nov 21, 2025
Update of the SAAS plateforme
Roman made a great job to make our SAAS alive, he worked a lot on different part of the code, front and back end. Now we continue to improve the workes he did.
I'll work again with Roman if I need to add new features.
I'll work again with Roman if I need to add new features.
WS
Weyland S.
Apr 23, 2025
Time off application
Roman is awesome. Great communicator, willingness to go the extra mile to make sure that the work was completed to a high standard. Generally a pleasure to work with.
JA
Joann A.
Sep 30, 2024
Buid SAAS project React + Laravel developer
Roman worked well and pretty fast on an urgent task. He even worked on weekend to be in time with my short dead line!
After that first jobs done, he continue to update the project to made a great SAAS for my client.
Now the SAAS is working well, made in few weeks and ready to have multi client on it.
I will work with Roman to update the SAAS project.
After that first jobs done, he continue to update the project to made a great SAAS for my client.
Now the SAAS is working well, made in few weeks and ready to have multi client on it.
I will work with Roman to update the SAAS project.
RK
Raif K.
Sep 21, 2023
Full Stack Web-Developer
Roman is a very friendly and communicative developer. He works correctly and is not afraid to go the extra mile to meet a deadline. He worked on two projects for me and I can highly recommend working with him.
About Roman
AI SaaS Developer | Laravel + React | LLM Integrations & Automation
100%
Job Success
Lviv, Ukraine - 1:18 am local time
workflows that survive real users, real edge cases and real
error rates.
Most AI projects fail after the demo. The prompt works, then
the queue backs up, the API times out, costs triple, and there's
no audit trail of what the model actually did. I build the
infrastructure layer that makes AI features shippable:
background jobs, retries, streaming, cost control, human
review, logging.
100% Job Success. 5.0 stars on every contract. 400+ hours.
WHAT I BUILD
— LLM features inside real products: Anthropic (Claude) and
OpenAI APIs — structured output, function calling, RAG,
streaming responses, prompt versioning, token/cost control
— Document AI: parsing, extraction, classification and
validation pipelines. Built these for KYC/AML compliance,
where a wrong answer is a legal problem, not a bad UX.
— Vision & multimodal: image recognition workflows (OCR,
photo-to-structured-data), document scanning
— AI agents & automation: Telegram/Slack bots, autonomous
task runners with tool access, scheduled agent workflows
— The product around the AI: multi-tenant SaaS, subscription
billing, admin dashboards, role-based access, usage metering
STACK
Laravel 12, PHP 8.3, React + TypeScript, Inertia.js,
PostgreSQL, pgvector, Redis, queue workers, Laravel Horizon,
Node.js, Docker. Anthropic API, OpenAI API, Claude Code.
Production experience in Vue.js, Rails, Next.js.
SELECTED WORK
— Compliance platform (KYC/AML): multi-tenant system with
three identity-verification providers, automated document
generation, encrypted payload handling and e-signature
workflows. AI-assisted document processing on top of a
fully auditable pipeline.
— Autonomous dev agent: a Telegram bot wired to the Anthropic
API with server access — I send a task in chat, the agent
plans it, executes it and reports back. Built it because I
wanted to ship from my phone. It works.
— Finance SaaS (my own product, live): automated tax
calculations and reporting for sole proprietors, with
AI-assisted document handling.
— SaaS platform rebuild (5.0 rating): "Roman made a great job
to make our SaaS alive, he worked a lot on different part of
the code, front and back end."
I use AI-assisted development daily — which means I ship
faster than my hourly rate suggests, and I know exactly where
these tools break. That second part is what you're actually
hiring.
HOW I WORK
Written plan before code. Daily written progress. Clean,
tested, documented commits. Europe hours with US overlap.
I communicate in writing — Slack, Upwork, Loom, detailed PRs —
and I'm direct about scope and feasibility. If your AI idea
won't work reliably, I'll tell you before you fund it, not
after.
Send me what you're trying to automate and I'll tell you
whether an LLM is the right tool for it — plenty of times
it isn't.
Steps for completing your project
After purchasing the project, send requirements so Roman can start the project.
Delivery time starts when Roman receives requirements from you.
Roman works on your project following the steps below.
Revisions may occur after the delivery date.
Initial discussion