01
Constraints over conventions
A unique index is a promise the database keeps. An if already_processed branch is a promise a developer remembers. On money paths, only one of those survives a refactor.
Open to senior full-stack & fintech work
Payments,ledgers &systems thatmust not drift.
Full-stack developer with 4+ years shipping production systems end to end — React and Next.js on the front, FastAPI, NestJS and Flask behind, PostgreSQL underneath, running on infrastructure I provision and maintain myself.
- Based in
- Ajmer, India
- Experience
- 4+ years
- Focus
- Fintech · payments
Rustam Khan
Full-Stack Developer
Scroll
TypeScript
NestJS
Next.js
React
Python
FastAPI
PostgreSQL
Redis
Docker
TypeScript
NestJS
Next.js
React
Python
FastAPI
PostgreSQL
Redis
Docker
TypeScript
NestJS
Next.js
React
Python
FastAPI
PostgreSQL
Redis
Docker
TypeScript
NestJS
Next.js
React
Python
FastAPI
PostgreSQL
Redis
Docker
About
RUSTAMKhan
I build systems where being wrong costs money.
- Role
- Full-Stack Developer
- Based
- Ajmer, Rajasthan · India
- Experience
- 4+ years, 25 systems shipped
- Focus
- Payments · ledgers · platforms
Most of what I build handles money. A multi-currency wallet platform on Cameroonian mobile-money rails. A P2P crypto marketplace where the API server is mathematically incapable of moving funds. An e-commerce refund engine that will not pay out cash the business has not yet been remitted.
That shapes how I work. I prefer guarantees the database enforces over checks a handler remembers to run — append-only ledgers instead of mutable balance columns, unique constraints instead of if already_processed, state machines pinned by tests instead of status strings.
I own the whole path: architecture, schema, API, frontend, Flutter apps, CI, VPS, nginx, backups and the restore script that proves the backups work. When something breaks at 2am in a timezone seven hours away, there is no one else to escalate to — so it is built not to.
01
0
Systems shipped
built, deployed, maintained
Fintech · marketplaces · edtech · embedded
02
0M
Lines shipped
Python · TypeScript · Dart
Counted with wc -l, excluding dependencies
03
0+
API endpoints
designed and documented
FastAPI · NestJS · Flask · Express route decorators
04
0+
Database tables
modelled and migrated
PostgreSQL · MongoDB · MySQL, across 900+ migrations
Counted from the repositories themselves — dependency files, route decorators, schemas and migration history. Not estimated.
Selected work
Twenty-five systems shipped.
Ordered by scale — largest first. Every figure was counted from the repository itself: routes, tables, tests, migrations. Each case study states its honest weaknesses too.
Fintech · Central Africa
QuataPay
Mobile-money & card payments platform
A full payments platform for Cameroon — wallets, agent cash-in/cash-out, merchant POS, bill pay, remittances and virtual cards — on live MTN MoMo and Orange Money rails.
1,390
API endpoints
272
DB tables
687k
Lines of code
303
Migrations
3
Flutter apps
80%
Coverage gate
FastAPIPython 3.12SQLAlchemy 2 asyncPostgreSQLRedisCeleryNext.js 16+4
Crypto · P2P exchange
QuataTrade
P2P crypto marketplace with escrow
A peer-to-peer USDT marketplace for Central Africa where the platform holds funds in escrow until both sides confirm — with a bank-grade double-entry ledger underneath.
100%
Branch coverage on money paths
554
Test blocks
9
Escrow states
NestJS 11FastifyKyselyPostgreSQL 16Redis+6
EdTech · India
EByAi
AI exam-prep for 165k+ questions
An exam-preparation platform for Indian competitive exams — JEE, NEET, CAT, CLAT, NDA, AIIMS-PG — with an AI doubt-solver, adaptive practice and mock tests across web, Flutter and React Native.
165k+
Tagged questions
61
Prisma models
154k
Lines of code
NestJS 11PrismaPostgreSQL 17 + pgvectorNext.js 16React 19+5
Multi-vertical marketplace
Abaqwa
Six booking verticals, one platform
A Cameroon-first super-app putting hotels, ride-hailing, parcel delivery, intercity bus, car rental and errands into one customer app — with a driver app, hotel-staff app and a large admin console behind them.
1,276
Python tests
874
API endpoints
3
Flutter apps
FastAPISQLAlchemy 2 asyncPostgreSQLRedisNext.js 16+5
B2B SaaS · India
Impex Info
Rescuing an unversioned production service
A B2B trade-intelligence service where importers search real customs records — a background worker scrapes the provider, builds an encrypted Excel report, uploads it and emails the customer.
4→1
Services consolidated
1
Service had no VCS at all
112k
Lines of code
FlaskPythonPostgreSQLReact 18Vite+4
B2B SaaS · India
SCM Insights
Trade intelligence, best SSR ratio in the fleet
A supply-chain and trade-intelligence platform for Indian importers and exporters — search customs shipment records, analyse trade flows, export reports — with a companion directory product sharing its backend.
24/31
Pages server-rendered
155
Flask routes
6 mo
Longest-running project
FlaskPythonPostgreSQLNext.js 16React 19+4
Agency platform · India
Kayease Global
Agency site, HRMS and a Flutter attendance app
The whole digital surface of a Jaipur software agency — the public marketing site that sells three SaaS products, the internal HR and employee portal behind it, and a Flutter app staff clock in with.
104
App Router pages
52
Server-rendered
87k
Lines of code
Next.js 16React 19Tailwind 4Redux ToolkitFramer Motion+6
Embedded · reverse engineering
KS Dairy DPU
Reverse-engineering milk-collection firmware
Recovering the behaviour of a commercial milk-collection terminal from its encrypted firmware — decrypting the image, mapping the hardware, and reconstructing the pricing maths that decides what a farmer is paid.
117,936
Bytes decrypted
2,116
Strings recovered
20/20
Display pins mapped
3
Pricing formulas reconstructed
7
Analysis documents
128×64
Display resolution
ARM Cortex-MCPythonFirmware analysisKS0108 / NT7108Serial protocolUSB host
The rest of the fleet
17 more01
QuataFood
Food delivery, three apps, one backend
Marketplace · logistics
370k lines
02Indian Cultura
Heritage commerce, two gateways, COD
E-commerce · India
193k lines
03Quata Digital
Corporate site + full internal business system
Corporate · internal ops
112k lines
04B.M. Birla Planetarium
Show ticketing with a counter POS
Ticketing · public institution
77k lines
05QuataAi
Self-hosted AI, no vendor in the loop
AI platform · developer tooling
57k lines
06QuataSeo
infrastructureMulti-tenant SEO engine, six products deep
Marketing SaaS
47k lines
How I work
Guarantees the database keeps.
Six rules that survived contact with production. Every one of them cost something to learn.
02
History is authoritative
Balances are derived from append-only entries, not stored in a mutable column. When a customer disputes a transaction eight weeks later, the entries are the evidence.
03
Integers, never floats
Money is held in minor units end to end, passed as strings over the wire so float precision never touches it, and formatted only at the display layer.
04
Prove it, don't assert it
100% branch coverage on the ledger, escrow and fee modules — with fault-injection tests that deliberately trigger serialization failures and deadlocks.
05
State the weaknesses
Every project I hand over comes with its honest gaps written down. A portfolio that only lists wins is a portfolio you cannot calibrate against.
06
Own the whole path
Schema to nginx config. If I did not provision the box and test the restore script, I do not really know whether it is production-ready.
Stack
Six disciplines, one owner.
The bars are counts, not confidence. Each one shows how many of the 25 projects above actually ship that tool — measured from their dependency files, not self-assessed.
01
Frontend
App Router by default. Server components where they earn their latency, client components at the leaves.
Next.js 1622
React 1912
Framer Motion5
Redux Toolkit5
Also TypeScript · Tailwind CSS v4 · TanStack Query · Zustand · GSAP · shadcn/ui · Radix UI · MUI · Chakra UI
02
Backend
Python where the data work is heavy, Node where the type contract matters most. Async everywhere.
FastAPI10
Express4
Celery3
NestJS 113
Also Flask · Node.js · SQLAlchemy 2 async · Prisma · Kysely · BullMQ · REST · GraphQL · WebSockets
03
Data & storage
Postgres unless there is a reason. Migrations always. Backups with a restore script that has been run.
PostgreSQL 1713
Redis4
MongoDB3
Alembic1
Also pgvector · PostGIS · MinIO · Firebase · Cloudflare R2 · SQLite
04
Payments & security
Double-entry ledgers, integer minor units, idempotent webhooks. Guarantees the database enforces.
Razorpay2
Stripe2
argon21
PayGlocal1
Also Double-entry ledger · Escrow state machines · MTN MoMo · Orange Money · PhonePe · JWT + refresh · TOTP 2FA · WebAuthn · RBAC · Hardened CSP
05
Mobile
Ten Flutter apps across four product families, each on a shared typed Dart SDK.
Flutter5
Expo1
Riverpod1
Also Dart · go_router · Dio · Drift · React Native · Biometrics · FCM push
06
Infrastructure
I provision the box, write the systemd unit, wire the CI and test the restore. No one else to escalate to.
Docker5
systemd5
GitHub Actions2
Caddy1
Also Docker Compose · nginx · PM2 · VPS · Vercel · Prometheus · Sentry · Playwright · pytest · Vitest · Testcontainers
Path
Trainee to sole owner of production.
Five roles, four years, and a freelance practice running alongside all of it.
- 2026
Aashita Technosoft
NowFull Stack Developer
Jan 2026 — Present
Jaipur, India
- Lead development across client web platforms — React and Next.js frontends, Node.js and Python backends, PostgreSQL and MongoDB.
- Own architecture, code review, deployment and ongoing maintenance on VPS infrastructure.
- 2025
Kayease Global
Full Stack Developer
Jul 2025 — Dec 2025
Jaipur, India
- Built and shipped client web platforms end to end, including admin dashboards, blogs and career portals.
- Improved load performance through code splitting, lazy loading and a Vite migration.
- 2024
Microsoft — via Teleperformance
Technical Support Executive
Aug 2024 — Jul 2025
Jaipur, India
- Resolved escalated technical issues for enterprise and consumer customers.
- Developed the diagnostic discipline and clear written communication that now carries into client work.
- 2023
Dice Academy
Web Developer Intern
Jan 2023 — Jun 2023
Delhi, India
- Built responsive interfaces and contributed to live client projects across the frontend stack.
- 2022
Sparks To Idea's
Web Designer Trainee
Jun 2022 — Jul 2022
Ahmedabad, India
- Introductory training in web design fundamentals and responsive layout.
Alongside
Independent Full-Stack Developer
2021 — Present
- Freelance work makes up the bulk of the 25 systems documented here — across fintech, e-commerce, education, healthcare, NGOs and digital media.
- End to end: architecture, React/Next.js frontends, Node.js/Python backends, databases, payments and VPS deployment, with ongoing client support.
Education
B.Tech, Computer Science
NIMS University
2020 — 2024
Intermediate (PCM)
Prince Academy
2019 — 2020
Languages
EnglishProfessional
HindiNative
Several client projects are not listed publicly — they are covered by non-disclosure agreements.
Open to senior full-stack & fintech work
Let’s build something that has to be right.
Payments, ledgers, marketplaces, or a platform that has outgrown the person who built it. Tell me what breaks and I will tell you honestly whether I am the right fit.
- Capacity
- 40 hrs / week
- full-time
- Earliest start
- 2 weeks' notice
- from signed scope
- Timezone
- IST · GMT+5:30
- 4+ hrs overlap with EU, 3+ with US East
- Location
- Remote worldwide
- Ajmer, India