Portfolio — Full Stack Engineer

Muddasar
Hussain

Full Stack Engineer · Ruby on Rails & React · B2B SaaS

Building the billing systems, client workflows, and APIs that make SaaS products actually work.

Ruby on Rails React PostgreSQL Stripe B2B SaaS

Available for new opportunities

LinkedIn Get in touch

Where I've shipped

Client names and references available on request. Public work is anonymized to respect confidentiality.

B2B SaaS Product engineering · appointments, billing & client workflows

Notifications at scale Transactional SMS · Twilio · TCPA compliance · retry infrastructure

Billing & payments Credit systems · Stripe · atomic transactions · zero double-charge

Full-stack delivery Ruby on Rails · React · PostgreSQL · production SaaS

How I can help

Shipping the parts of your SaaS that are hard to get right

Stripe and PayPal, subscriptions, marketplace payouts, and credit systems — with idempotent webhooks, atomic transactions, and zero double-charges.

Transactional SMS and email with Twilio, Mailchimp, and Mandrill — consent handling, retries, and deliverability you can rely on.

REST and GraphQL APIs plus third-party integrations (Stripe, Zoom, Google Meet, calendars) wired up end-to-end with solid error handling.

Ruby on Rails and React features from database to UI — built for production SaaS, with tests and an eye on performance.

Companies I've worked with

Teams I've shipped production software for — B2B SaaS, billing, and full-stack product work.

Client feedback

Proven in production

$0 Duplicate charges in production across thousands of transactions

+35% Notification deliverability after integration reliability work

−45% Data fetch time after moving real-time ops to GraphQL

+20% Revenue conversion from a Stripe-based credit monetization flow

Have a billing, notifications, or integration problem that needs to ship reliably?