Available for new projects and contract work

Hey, I'm_

Jubayer Hossain

Founders and product teams hire me to own the full stack — mobile, web, and backend — from first commit to live users. No handoffs, no silos, no gaps.

See the work Get in touch

Or book a free 30-min call

$ git log --oneline # 10+ products · 0→1 specialist

In production

Built. Shipped. Running.

To respect client confidentiality, specific brand names are omitted. However, I engineered every platform below from the ground up, and live production links or private walkthroughs are available upon request.

AI-native · Sports & Health

AI-powered sports performance app

Role

Sole engineer

FlutterNestJSMongoDBStripeAI scoringGDPR-oriented

A multi-persona mobile product combining AI-driven performance scoring, wearable health data, and injury-risk analysis — with a subscription-gated entitlement system and deep security across the full stack.

Designed five distinct user personas with role-based navigation — athlete, coach, scout, analyst, admin — each with scoped data access.
Built the AI scoring engine: raw wearable + health data → risk insights, performance charts, and paywalled reports.
Implemented the full payment and entitlement layer: Stripe subscriptions, packaged access tiers, idempotent webhooks, and a pending→active state machine to prevent false paid states.
Engineered layered security: payload encryption before leaving the device, TLS pinning, runtime threat detection, and CSRF-safe auth.
Sole author of the backend (auth, health data, billing, messaging, org management) and all client-facing surfaces.

Outcome

In production with paying subscribers — live app links and a private walkthrough available on request.

Read the full case study →

E-commerce · Retail

E-commerce platform, built from scratch

Role

Primary contributor

React + ViteFastAPIMongoDB + RedisRazorpayAzure CDN

A complete storefront, CMS, and admin console — product catalog, cart, checkout, coupons, accounts, shipping, and a media pipeline — built and shipped to production.

Built the entire customer-facing storefront: browse, product pages, cart, wishlist, checkout, and account management from scratch.
Designed and authored 15+ backend domains: catalog, orders, carts, coupons, shipping settings, and media management.
Implemented payments end-to-end with Razorpay — idempotent webhooks, atomic stock decrements, and transactional emails so nothing lands in a half-mutated state.
Built OTP login with secure cookie sessions, CSRF protection, and rate-limited auth to prevent abuse.
Designed the media pipeline: upload → multi-size WebP conversion → Azure CDN delivery, keeping product images fast globally.

Outcome

Shipped to production and handling live orders daily — private walkthrough available on request.

Read the full case study →

Multi-tenant SaaS · Elder care

Multi-tenant elder-care SaaS

Role

Primary contributor

FlutterNext.jsNestJSMySQLBullMQAzure

A complete care ecosystem: patient app, caregiver app, tenant and super-admin consoles, and the API — with multi-tenant RBAC, a booking-to-medication care loop, geo-validated service areas, and GST-aware invoicing.

Built white-label patient and caregiver Flutter apps sharing a single codebase, configured per tenant via build flavors.
Engineered the multi-tenant RBAC system: orgs, care centers, and staff each with scoped permissions — a wrong role getting the wrong data was never acceptable in an elder-care context.
Built the full care loop: booking, caregiver assignment, roster management, medication tracking, and attendance — all connected.
Implemented GST-aware billing, multi-payment invoicing, and branded PDF receipts with correct tax breakdowns.
Added geo-validated service areas and in-app notifications (BullMQ) so caregivers and patients only see what is relevant to their region.

Outcome

Live across multiple tenant organizations — private walkthrough available on request.

Read the full case study →

Have a product that needs this? →

By the numbers

Scale, complexity, and shipped results.

Every metric below comes from real systems running in production.

products shipped

engineered end-to-end to production

products from scratch

from first commit to live users

client platforms

web · iOS · Android · desktop

industries delivered

sports, health, e-commerce, logistics, and more

How I work

Deep expertise, broad reach.

The core engineering capabilities that I own end-to-end — backed by the crucial product skills that every real system needs to scale securely.

iOS & Android apps

Production iOS + Android apps built from a single codebase — multi-role navigation, localization, offline sync, wearable integrations, shipped to TestFlight and stores.

Multi-persona navigation
Offline-first sync
Health & wearable pipelines

Web apps & dashboards

Marketing sites, dashboards, admin consoles and full-scale storefronts in Next.js and React — built fast, SEO-optimized, and engineered for real-world production traffic.

Next.js · React · Vite
Admin & ops consoles
Performance & SEO

AI features, production-ready

Real AI integrations that ship — RAG pipelines, scoring engines, natural-language query translation, and report generators that make products genuinely smarter.

RAG & semantic search
Scoring / report generators
NL → structured filters

Scalable backends & APIs

NestJS, FastAPI and Node backends driving core business logic — deep RBAC, real-time sockets, relational + NoSQL databases, and architectures built to scale from day one.

REST APIs & auth
RBAC & real-time
Mongo · MySQL · Redis

Product & Infrastructure

Payments & entitlements

Subscriptions, packages and invoices end-to-end with Stripe and Razorpay — idempotent webhooks, pending→active state machines, no false paid states.

Security-minded builds

Payload encryption, TLS pinning, CSRF-safe cookies, RBAC and privacy-by-design baked in from day one — not bolted on at launch.

DevOps & deployment

Docker, CI/CD, CDN pipelines, and observability so "works on my machine" never makes it to the incident log.

The toolkit

Everything your product needs, on call.

I pick the right tool for the job — and I've shipped production code in all of these.

TypeScriptEverywhere

ReactComponents

Next.jsWeb apps

FlutteriOS + Android

Node.jsRuntime

NestJSNode APIs

FastAPIPython APIs

MongoDBStore

RedisCache

SQLRelational

TypeScriptEverywhere

ReactComponents

Next.jsWeb apps

FlutteriOS + Android

Node.jsRuntime

NestJSNode APIs

FastAPIPython APIs

MongoDBStore

RedisCache

SQLRelational

PythonML/scripts

StripePayments

RazorpayPayments

FirebasePlatform

DockerDeploy

CI/CDAutomate

Claude / GPTAI

RAG · LangChainAI

Socket.ioReal-time

AWS / AzureCloud

PythonML/scripts

StripePayments

RazorpayPayments

FirebasePlatform

DockerDeploy

CI/CDAutomate

Claude / GPTAI

RAG · LangChainAI

Socket.ioReal-time

AWS / AzureCloud

About

Building software end-to-end.

I build software because I genuinely enjoy the craft of turning a blank repo into a system that actual people use. I don't just write code — I care about the product, the architecture, and the business logic behind it.

My sweet spot is acting as a founding engineer for early-stage teams or embedding deeply to scale complex systems. Whether it's architecting a scalable backend in NestJS, building a multi-role Flutter app, or wiring up Stripe for a SaaS, I own the outcome end-to-end.

Founders trust me because I don't need hand-holding. I flag risks early, write clean and maintainable code, and treat your product with the same intensity as if it were my own.

LinkedIn profile

Own the loop

Solo-built a 5-persona mobile app across every client surface, then stayed for the production launch and debugged the live incidents after the release. There's no hand-off wall — nothing gets thrown over one.

Adversarial by default

Health data, payments, and credentials aren't checkbox features. I build every system as if someone is actively trying to break it — because once it's live, someone always is.

Live first, perfect second

Production is the only honest test. CI/CD and containerized deploys are standing in week one, and durability fixes come from real field failures — not from simulations I'd have to invent.

Jubayer Hossain

Founding Product Engineer

Currently

Available for new projects & contracts
Building end-to-end products
Working remotely, globally

Testimonials

Words from the people I build with.

A few of the messages I've received after delivering — from clients and from teammates. Names stay private; the roles and the context are what matter.

At first glance, it's ❤️

PMProduct Manager

A client's PM, on first look at the product we had just shipped together.

Name withheld by request

I don't have any hesitation sharing this. When we started working together three years ago, front-end aesthetics weren't your strength. You've come a long way. Keep it up.

CTO

A CTO I've built with over several years, who has watched this craft improve up close.

Name withheld by request

You don't just follow the requirements — you come back with questions and edge cases, which helped rethink features for better use cases. I also like the way you solve things by splitting them into smaller problems.

Senior Engineer

An engineer who has seen me operate up close across shared builds and teams.

Writing

Notes from building real products.

English4 min

Architecting a Marketplace: 1 Backend, 5 Surfaces

How I engineered a unified backend to serve a driver app, admin panel, supplier portal, customer website, and a WhatsApp bot without collapsing into spaghetti code.

Aug 1, 2026Read →

English3 min

Production AI: Integrating OpenAI & Perplexity in NestJS

Toy AI wrappers are easy. Building reliable, asynchronous AI pipelines in a production NestJS enterprise environment is a different game entirely.

Jul 15, 2026Read →

English3 min

The 0-to-1 Playbook: Flutter + NestJS

The mental models and architectural decisions required when you are the sole engineer building a mobile app, an admin panel, and the backend API.

Jun 10, 2026Read →

See all posts

Contact

Let's build something real.

Whether you're a founder with an idea, a studio that needs a founding engineer, or a product team that wants a senior pair of hands — tell me what you're building and I'll reply fast.

Reach me directly

Connect on LinkedIn

Book a free 30-min call

Availability: open to new projects and contract work. Remote-friendly.