Scalable Next.js Commerce Upgrade

Budget: 8000 USD Deadline: 20 days

Hi Maxwell.

From the description, it looks like the product has already reached a stage where the business is growing faster than the current architecture can comfortably support — and this is usually the point where a well-structured refactor brings the most value, if done properly rather than superficially.

I’ve worked with Next.js + backend systems where the main focus wasn’t adding new features, but identifying real performance bottlenecks, stabilizing API behavior, and restructuring code so it can scale without constant regressions.

In your case, the sensible approach is to start with a proper diagnosis of the slow response times, fix the critical performance issues first, and only then move toward a clean API layer and a fully reliable Stripe flow.

I can review the repository, analyze the current architecture, and outline a clear refactoring plan with priorities and risks before any major changes are made.

Let's have a quick chat to discuss your project in detail. Expand

Budget: 8000 USD Deadline: 15 days

Hello!
We are dZENcode — a full-cycle digital product development company: from design and programming to integrations and post-release support.
We take projects from scratch and also work on existing solutions that need further development or improvements.

We can help refactor your Next.js and NestJS platform and improve the slow checkout flow.
1. What should we prioritize first in the refactor?
2. Are there any critical legacy modules or routes causing the slowdown?

You can find detailed information about our services and projects on our profile: Freelancehunt
Please review it — after that, we can discuss the details and agree on the next step.

⚠️ After clarifying all details, we will define the scope, the suitable cooperation format — task-based, outsource, or outstaff — and the final cost.

Why projects are guaranteed to reach release with us:
💎 10+ years providing IT services;
🔥 90+ in-house specialists;
🚀 250+ public reviews since 2015;
⚙️ We support products under SLA after launch;
✅ We work under NDA and a company contract! Expand

Budget: 8000 USD Deadline: 30 days

Hello.

I'm NodeJS developer. I have experience with Next.js and NestJS. Ready for work. Lets talk.

Budget: 8000 USD Deadline: 60 days

Hi,

This project is right in my wheelhouse — I've worked with exactly this stack: Next.js 14, NestJS, PostgreSQL, Auth.js, and Stripe.

Here's how I'd approach your priorities:

1. Legacy refactoring — I'd start with profiling slow endpoints (query analysis, N+1 issues, missing indexes in Postgres) before touching any code. No blind rewrites.
2. Clean API layer — REST with OpenAPI docs and Postman collection included. Happy to add GraphQL endpoints where it makes sense.
3. Stripe checkout — full end-to-end flow in test mode: Payment Intents, webhook handling, idempotency keys, and graceful failure paths.

On the acceptance criteria:
- p95 < 200ms under 500 concurrent users is achievable with proper DB indexing, query optimization, and NestJS caching — I've hit similar benchmarks before.
- TDD is my default workflow; I'll keep Jest green and extend coverage where it's missing.
- I'm comfortable recording Loom PR walkthroughs so your internal team stays in the loop on every architectural decision. Expand

Budget: 8000 USD Deadline: 1 day

Good day.

I have experience in refactoring eCommerce projects using Next.js + NestJS + PostgreSQL, including optimizing checkout/catalog flows and Stripe integration.

I can quickly connect to legacy code and focus on the main priority — reducing server response time and eliminating bottlenecks without risky rewrites.

I have experience with k6/performance testing and CI workflows through the GitHub PR process.

I am ready to quickly engage in the project.

Budget: 8000 USD Deadline: 7 days

Hello, I worked on an online store for dropshipping using Next.js + NestJS that processed over 800 orders a day and had an API response time of less than 150ms under a load of 1000 users.

Maxwell, could you please tell me which specific legacy modules have the most impact on the server response time during the checkout process?

I have experience optimizing similar e-commerce platforms with the same technology stack. I have worked with PostgreSQL indexing, NestJS caching, and Stripe webhook processing.

I suggest we get in touch; I will provide you with a free technical consultation and we can create a development plan + I will tell you about my team! ⚡

Budget: 8000 USD Deadline: 60 days

Good day. I, an individual developer, offer my services for a deep refactoring of your platform. I have over 4 years of commercial experience in development with Next.js, NestJS, and PostgreSQL 15, working officially through a sole proprietorship and taking full responsibility for the code without intermediaries. I independently localize the causes of high server response times using logging and profiling of database queries. I guarantee optimization of p95 < 200 ms through refactoring heavy SQL queries, setting up proper relationships in models, and caching. I will fully rewrite the Stripe checkout flow (test mode, rollbacks, webhooks) and integrate the Postman collection. Each of my PRs will be accompanied by a Loom video for your team. Examples of my approach to scalable architecture and high Lighthouse scores can be found at 3magency.co and https://vilors.studio/.

Budget: 8000 USD Deadline: 10 days

Hello. Our small team is ready to engage in the refactoring and optimization of your web platform, based on 4+ years of experience in developing high-load full-stack systems. We will clearly follow your priorities: 1) Code profiling and eliminating bottlenecks in NestJS/PostgreSQL to handle k6 load with 500 concurrent users; 2) Covering new endpoints with Jest tests and auto-generating OpenAPI documentation; 3) Finalizing Stripe integration with secure webhook processing using signatures (Stripe-Signature). All pull requests will be accompanied by a detailed Loom review of architectural solutions. You can assess the quality of our commercial solutions at the following links: freshagro.com.ua, farfieworldwide.com, rivnekolo.com. We are in touch and ready to explore the current repository.

Budget: 8000 USD Deadline: 40 days

Good day. My colleague and I are interested in your project, as we have specialized in performance optimization of complex TypeScript systems and payment gateway integration for the last 4 years. To eliminate the high TTFB on the Next.js 14 catalog pages, we will optimize rendering strategies (ISR/SSR) and set up efficient Data Fetching with the NestJS API. In NestJS itself, we will check the operation of interceptors and optimize connection pools with PostgreSQL 15. We will implement a secure and fault-tolerant Stripe Checkout flow with full validation through DTO (class-validator) and coverage of edge cases for payment failures. Our level of work with code and architecture is reflected in the projects drkukharevich.rivne.ua, crave-agency.com.ua, jk-solution.com.ua.

Budget: 8000 USD Deadline: 50 days

Hello! My partner (full-stack architect + QA/DevOps) and I are ready to take on the refactoring of your e-commerce platform. We have over 4 years of experience working with Next.js and NestJS architecture. Your goal of p95 < 200 ms under the k6 script is absolutely clear to us: we will conduct an audit and refactor the NestJS services, eliminate N+1 queries in PostgreSQL, set up proper indexes, and optimize session checks in Auth.js (NextAuth). We will move the processing of Stripe webhooks to asynchronous rails so that heavy database write operations do not block the HTTP response to the user. We guarantee 100% green CI in Jest and ESLint, will prepare OpenAPI (Swagger) documentation, and record a Loom video with a detailed breakdown of the PR for your team. Our development experience and benchmarks of fast systems: hyperfi.tech, espressolab.com.ua, hudi.com.ua.

Budget: 8000 USD Deadline: 11 days

Hello! My partner and I have been working as a team for 4 years on high-load web platforms and have experience with Next.js, NestJS, PostgreSQL, Stripe, and performance optimization. We have a good understanding of legacy code issues and server response bottlenecks — we can quickly engage in refactoring, optimizing the API/database layer, cache strategy, and checkout flow without losing system stability. We work with TDD, Jest, OpenAPI, CI/CD, and scalable architecture, so we can maintain clean production-ready code and a safe rollout of changes. Examples of our work: apple-family.com.ua/uk, 3magency.co

Budget: 8000 USD Deadline: 35 days

Welcome! We are a team of developers with 4 years of experience in creating turnkey online stores and supporting complex web applications. Scaling commercial platforms using Next.js is the best solution for your business, as it combines ultra-high performance and maximum potential for search engine optimization (SEO). We will migrate your project to the modern Typescript and Next.js stack, optimize the database structure, update the UI/UX interfaces, and integrate stable payment systems.
Examples of our expertise in e-commerce development can be found at the links farfieworldwide.com, freshagro.com.ua, and espressolab.com.ua.
Contact us via private messages to discuss the technical task.

Budget: 8000 USD Deadline: 30 days

Hello!
My name is Alex, and I represent NC-1, a dedicated development group. For over five years, we have been building e-commerce products, high-load, and distributed systems.
I would like to propose our specialist for your migration project on an outstaffing basis — a Senior Full-Stack Developer / Team Lead (5+ years of experience).

🛠️ Technical Stack:
Core & Frontend: TypeScript, React, Next.js, RTK, Zustand, Effector, Tailwind
Backend & DB: Node.js, NestJS, Express, PostgreSQL, TypeORM,
RedisInfrastructure: Docker, Linux, Socket.IO, RabbitMQ

🎯 About the Developer:He has over 5 years of extensive experience in the IT industry, with a particular focus on web development, e-commerce, and high-load solution creation. As a committed and outcome-driven IT professional, he possesses a passion for programming and delivering clean, production-ready code.

🚀 Direct Fit for Your Migration & Performance Goals:

High-Load & Optimization: Deep experience with query optimization and Redis to eliminate high server response times and meet your $p95 < 200\text{ ms}$ requirement.

Your Exact Stack: Ready to jump immediately into your Next.js 14, NestJS, and PostgreSQL repository.

Testing & Payments: Proficient with Jest (TDD), CI/CD workflows, secure Auth.js integration, and complete end-to-end Stripe setup with robust webhook handling.

Team-Ready: As a Team Lead, he is fully prepared to provide OpenAPI documentation, Postman validation, and detailed Loom video walk-throughs for your internal team.

Best regards,
Alex
NC-1 Development Group Expand

Budget: 8000 USD Deadline: 10 days

Hi there! Your stack and acceptance criteria are very clear, and I can jump into the existing repo and refactor for speed without breaking your delivery rhythm. I have worked in Next.js 14 and NestJS codebases where the real wins come from fixing data access patterns, reducing server work per request, tightening caching, and removing hidden N plus 1 queries that quietly hurt catalogue and checkout.

I can start by profiling the slow paths under load with your k6 script, then work module by module so every change is measurable. I will keep Jest green, follow your ESLint rules, and make sure Lighthouse stays healthy while we improve TTFB and p95 latency. For the API phase, I can deliver clean REST or GraphQL endpoints with OpenAPI documentation and a Postman collection that matches real use cases, not just happy paths. For Stripe, I will harden the checkout flow end to end in test mode, add webhook idempotency, signature verification, and graceful failure states so orders never get stuck in an unclear status.

One idea that will make your team move faster long term is a Performance Contract that lives in the repo. It is a small set of automated benchmarks that run in CI on key routes like catalogue search and checkout, so regressions get caught before merge and you stay under the p95 target as the product grows.

https://app.cookiecad.com
https://www.clicknova.de

Budget: 8000 USD Deadline: 1 day

Good day! I have reviewed the task and am ready to start. I will do it efficiently and very quickly. I have over 5 years of experience in development. I live in Europe, so there will be no issues with power or connectivity.

Some projects I have completed and participated in:

http://contentbuilder.ai/ - I officially worked at a startup that allows creating presentations, courses, etc. using AI.

sarafan.com.ua - website of a volunteer company.

bionrgg.com (https://bionrgg.com/) - my solution for creating digital business cards for volunteers; I am a partner of the volunteer company Sarafan, which is a partner of Silpo.

https://freelancehunt.com/showcase/work/sayt-avtomobilnyih-poputchikov/1715396.html Expand

Budget: 8000 USD Deadline: 111 days

Hello!

We are a development team with strong experience in high-load eCommerce platforms and modern TypeScript ecosystems, including Next.js, NestJS, PostgreSQL, Stripe, and scalable API architectures.

Your project aligns very closely with the kind of work we typically handle — especially performance-focused refactoring of legacy systems and migration toward fully type-safe architectures.

We can help you with:

* deep refactoring of legacy monolith code without breaking existing functionality;
* identifying and eliminating backend/frontend performance bottlenecks;
* optimizing API response times and database queries for high concurrency workloads;
* building clean REST/GraphQL APIs with proper architecture and scalability in mind;
* secure Stripe checkout integration with webhook handling and failure recovery flows;
* maintaining strict code quality standards with TDD, Jest, ESLint, CI pipelines, and Lighthouse performance targets.

We have practical experience with:

* Next.js 14 App Router architecture;
* NestJS modular backend systems;
* PostgreSQL optimization and query tuning;
* Auth.js authentication/session flows;
* Stripe subscriptions and payment processing;
* performance profiling, caching, and load optimization under production traffic.

We are comfortable working directly in GitHub-based workflows with PR reviews, CI/CD pipelines, documentation standards, and recorded technical walkthroughs for internal teams.

The performance target of p95 API response time below 200ms under concurrent load is absolutely realistic with proper profiling and architecture optimization, and we would be happy to help stabilize and scale the platform further.

Ready to discuss the current architecture, bottlenecks, and roadmap in more detail. Expand

Budget: 8000 USD Deadline: 14 days

Good day.

The project looks technically serious and closer to production-grade refactor/performance engineering than to "ordinary" fullstack development. Especially due to the legacy monolith, performance targets (p95 < 200ms with 500 concurrent users), Stripe/webhooks, and requirements for CI/TDD workflow.
Before confirming the full scope, I want to conduct a short technical audit of the current state of the system and bottlenecks. This will allow:
• to honestly assess the risks,
• to understand the actual volume of legacy,
• to determine if I can handle the task independently,
• and to provide an adequate estimate on time/stages.
The audit will take about 1 day after gaining access to the repository/environment.
After the audit:
• I will provide honest feedback on feasibility,
• I will propose a roadmap,
• and a breakdown by stages.
My rate: $10/hour. Expand

Budget: 8000 USD Deadline: 50 days

Hello, Maxwell.

As a full stack developer that have a very extensive experience in next.js, nestjs backend, and rest api integration, postgresql database, and stripe payment gateway integration.

Based on this experience, I am ery interested on this project and I am ready to start right now.

Feel free reach out to me any time to discuss more detail.

Thanks, Youssef.

Budget: 8000 USD Deadline: 14 days

Вітаю! 👋

Маю досвід роботи з production e-commerce платформами, рефакторингом legacy-коду, оптимізацією API performance, checkout flow, Stripe webhooks та побудовою типобезпечної архітектури на сучасному стеку.

Релевантний стек:

Frontend:
Next.js 14
React
TypeScript
SSR / Server Components
Lighthouse / Core Web Vitals optimization

Backend:
NestJS
Node.js
PostgreSQL
REST / GraphQL API
OpenAPI / Swagger
Auth.js sessions

Payments:
Stripe Checkout / Payment Intents
Stripe webhooks
failure handling
test mode E2E payment flow
Testing / Quality:
Jest
ESLint
TDD workflow
Postman collections
k6 load testing
GitHub PR-based workflow

З подібного досвіду:

e-commerce checkout/API optimization;
production backend refactoring;
PostgreSQL query optimization;
Stripe payment flows;
Next.js/NestJS API integrations;
CI-based delivery with tests and review.

Готовий переглянути репозиторій, k6 script, поточні slow endpoints і запропонувати план першого optimization sprint.

З повагою,
Андрій Expand

Budget: 8000 USD Deadline: 50 days

Hello,

I’m a full-stack developer with strong experience in high-load web applications and modern TypeScript stacks, including Next.js, NestJS, PostgreSQL, Stripe, and Auth.js. Your project is especially interesting because it combines legacy refactoring, performance optimization, and scalable architecture — areas I work with regularly.

I have experience improving API performance, reducing server response times, optimizing database queries, and refactoring unstable legacy codebases into maintainable production systems. I’m comfortable working with TDD workflows, Jest, ESLint, CI pipelines, OpenAPI documentation, and performance testing tools such as k6 and Lighthouse.

I can help with:

* Refactoring performance-critical legacy modules
* Optimizing checkout and catalog response times
* Building clean REST/GraphQL APIs
* Secure Stripe integration with webhook handling
* Maintaining test coverage and code quality standards
* Clear PR documentation and recorded architecture walkthroughs

I work comfortably inside existing GitHub workflows and focus on writing scalable, production-ready code with clean architecture and long-term maintainability in mind.

Available to start immediately.

Best regards Expand

Budget: 8000 USD Deadline: 8 days

I am a NextJs, React, NestJs developer. I am ready to take on this task.

Budget: 8000 USD Deadline: 60 days

Hello!

This is the type of project where it is important not just to write clean code, but to diagnose correctly — and then refactoring becomes obvious. This is how I approach similar tasks.

My experience with this stack:
I have worked with Next.js 14 (App Router + Server Actions), NestJS (modular architecture, guards, interceptors), PostgreSQL 15 (query optimization, indexes, connection pooling via PgBouncer), Auth.js and Stripe (webhooks, idempotency keys, handling failure paths). TDD + Jest is standard for me, no exception.

What I will do in the first stage — refactoring:
Before writing any new code, I will conduct profiling: slow query log in Postgres, APM traces on NestJS services, analysis of the k6 script you already have. High server response times on checkout and catalog are usually one of three things: N+1 queries, missing indexes on hot-path tables, or blocking operations in synchronous code. After diagnostics — targeted refactoring with measurement before/after. The goal of p95 < 200 ms under 500 concurrent users is realistic if a few key bottlenecks are eliminated.

Next on the roadmap:
- REST + GraphQL API with OpenAPI documentation and Postman collection
- Stripe end-to-end: Payment Intent flow, webhook signature verification, retry logic, graceful failure paths
- PR review recorded on Loom with explanations of each architectural decision for your team
- CI remains green on every merge — this is not negotiable

Timeline: approximately 6–10 weeks depending on the depth of legacy debt (more precisely — after reviewing the codebase). Expand

Budget: 7999 USD Deadline: 30 days

Hello, Maxwell!

Your stack and priorities align very closely with the kind of systems I work on: performance-critical applications with growing architectural complexity that need to evolve without destabilizing production.

I have strong experience with Next.js, NestJS, PostgreSQL, Stripe integrations, and large-scale refactoring of legacy codebases. Most of my recent work has focused on improving backend response times, restructuring brittle application layers into maintainable domain-driven architectures, and introducing stricter type safety and test coverage without slowing delivery velocity.

What particularly caught my attention is the emphasis on measurable performance targets and engineering discipline:
— p95 latency targets under concurrency
— Lighthouse-sensitive frontend optimization
— OpenAPI-driven API design
— resilient Stripe webhook handling
— TDD-first workflow with CI enforcement

This is exactly the kind of environment where I’m most effective.

I’m comfortable profiling and eliminating bottlenecks across the entire request lifecycle: inefficient DB access patterns, SSR waterfalls, hydration overhead, caching strategy gaps, N+1 queries, over-fetching GraphQL resolvers, blocking middleware, and Stripe-related latency during checkout flows.

I can also provide clean PR walkthroughs and architectural reasoning documentation for your internal team.

Would be glad to discuss the current bottlenecks and review the existing architecture. Expand

Budget: 8000 USD Deadline: 40 days

Hi, Maxwell
Your project is the kind of migration where disciplined architecture matters much more than simply rewriting code because performance issues in hybrid monolith systems usually come from accumulated technical debt across database access rendering patterns caching and payment flows rather than one isolated bottleneck
I’ve worked on Next.js and NestJS based systems where the main focus was reducing response times under load while keeping the codebase maintainable and fully type safe

From your description the immediate priority is clearly backend and rendering optimization rather than feature development which is the correct approach before scaling APIs and payments further
I like that you already have CI Jest and ESLint in place because that makes iterative refactoring much safer especially when improving legacy modules under production constraints
Your p95 target under 500 concurrent users is realistic assuming the current bottlenecks are mostly query and rendering related rather than infrastructure limitations
For load validation I would continuously benchmark using the provided k6 scripts during refactor phases instead of waiting until the end because performance regressions are much easier to isolate incrementally
I'd like to discuss with you
Thank you

Budget: 8000 USD Deadline: 30 days

Hello!

I have experience working with the Next.js 14 + NestJS + PostgreSQL stack on production e-commerce projects and understand this task at the architectural level, not just the code. Refactoring legacy modules to achieve p95 < 200ms under 500 concurrent users is a realistic goal with the right approach to query optimization, connection pooling, and SSR caching.

I will refactor the legacy code while profiling bottlenecks, build clean REST/GraphQL APIs with OpenAPI documentation and a Postman collection, and implement a complete Stripe checkout flow with webhook handling and fallback paths in test mode. I will cover everything with unit tests (Jest), keep the CI green, and record a loom review of the PR for your team.

Please message me privately, and I will provide an exact cost and timeline for implementation.

Best regards, Mykola

Budget: 8000 USD Deadline: 40 days

Hello!
I’m very interested in your project. I have strong production experience migrating monolithic e-commerce platforms to a modern, type-safe stack using Next.js 14 (App Router) + NestJS + PostgreSQL, and I can start immediately.
My Understanding of Your Needs:

Primary goal: Significant performance improvement — reduce server response times on catalogue and checkout pages (target: p95 < 200ms under load).
Full refactor of legacy codebase while maintaining stability.
Clean architecture with proper separation (Next.js frontend + NestJS backend).
High-quality deliverables: strong testing, OpenAPI documentation, secure Stripe integration, and clear PR walkthroughs.

How I Will Approach This:
Phase 1 (Highest Priority – Performance & Refactor)
Deep audit of current bottlenecks (N+1 queries, inefficient Prisma/ORM usage, unoptimized API endpoints, heavy middleware, etc.)
Refactoring critical modules (catalog, product details, cart, checkout)
Database query optimization + proper indexing
Implementing caching strategies (Redis + Next.js cache)
API optimization (NestJS) + Data fetching improvements in Next.js

Phase 2
Clean REST/GraphQL API development
Hardened Stripe integration (Checkout + Webhooks + idempotency + error handling)

Phase 3
Full test coverage, OpenAPI docs, monitoring setup

My Relevant Experience:
Successfully migrated two mid-size e-commerce platforms from monolith to Next.js 14 + NestJS stack.
Achieved p95 response times under 180ms under high load in production.
Deep expertise with Auth.js (NextAuth), PostgreSQL, Prisma/TypeORM, Stripe Connect & Checkout, and TDD.

Estimated time: 3–4 weeks

I work with high transparency: daily updates, Loom videos for complex decisions, and maintain green tests + high Lighthouse scores on every merge.

Next Steps:
Would you be available for a short call this week? I can review your repository and give you a more precise estimate and action plan after seeing the current codebase.
Looking forward to working together on this transformation.
Best regards, Expand

Budget: 8000 USD Deadline: 21 days

Hello. My name is Roman, CVO of Echocode.Digital. We have an experienced team with 8 years of expertise in creating turnkey websites, mobile applications, and complex web systems. We specialize in developing modern, responsive, and high-performance solutions. Over 8 years of practice, we have formed a deep technical stack:
UI/UX Design: Interface design, creation of design systems, Wireframes, Mobile & Web UI (Figma, Adobe Creative Suite).
Frontend and interfaces: HTML, CSS, JavaScript, TypeScript, React.js, Next.js.
Mobile development: React Native and Flutter.
Backend and server logic: Node.js (NestJS), Python (FastAPI/Django), PHP (Laravel), WordPress.
Databases and storage: PostgreSQL, MySQL, MongoDB, Redis.
Infrastructure and DevOps: Docker, AWS, WebSockets, REST API, Git.
You won't have to separately look for a designer, backend developer, and frontend developer. Our team works in a unified manner, which eliminates misunderstandings between design and code, significantly speeds up development, and guarantees quality results from a single source.
Message us in private! We will discuss the details of your project, calculate exact timelines and budget. Ready to start soon!

Budget: 8000 USD Deadline: 30 days

Hello. I have been working with React and Node.js for more than 9+ years. Also, I have a lot of experience with Next.js and Nest.js. Could I see the project?

Budget: 8000 USD Deadline: 15 days

Hello! I will rewrite your platform, I have been working with NEXT.js for many years. I will complete your task quickly and efficiently.

My recent works
https://indexfast.pp.ua
https://mamamia.pp.ua
https://monitortest.pp.ua
https://keytest.pp.ua
https://florist-map.vercel.app

My portfolio: https://freelancehunt.com/ua/freelancer/romas6ka.html#portfolio
Message me, I can start working today. I would be happy to collaborate with you! Expand