Backend Engineer / System Architect

AhsanAtta

Backend systems for fintech, SaaS, and marketplaces where reliability has business cost.

Building backend systems for fintech, SaaS, and marketplaces where APIs, payments, data integrity, and reliability have to hold up under real production load.

Ahsan Atta

Currently building production backend systems at ZAPTA Technologies. Based in Pakistan.

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01Operational Proof

Production evidence behind the backend work.

API volume, relational modeling, user scale, latency improvements, request load, and real-time concurrency from shipped systems.

Production APIs
100+
Relational Models
75+
Active Users
300K+
API Latency Reduction
50%
Daily API Requests
10K+
Concurrent Sockets
500+
02About

Backend engineering where failure has business cost.

The focus is practical: keep critical workflows traceable, make service boundaries clear, reduce database pressure, and design systems that remain maintainable when usage, support load, and transaction volume increase.

Beyond backend systems, I work across the stack when the project needs it. On KashyBee I handled UI architecture and frontend integration end to end alongside the backend, using AI tooling to move faster without sacrificing correctness or production standards.

  • 01Find where requests wait before adding infrastructure.
  • 02Keep ownership boundaries explicit across users, roles, tenants, and panels.
  • 03Treat payment, wallet, and KYC workflows as audit-sensitive paths.
  • 04Design retries, rate limits, indexes, and migrations before pressure exposes them.
03Selected Expertise

Systems I build and stabilize.

  • Fintech Workflows

    Voucher redemption, wallet operations, settlements, commission calculation, transaction logging, and reconciliation paths.

    NestJSPostgreSQLPrismaTypeScript

  • Payments & Webhooks

    Stripe, PayPal, Paystack, SasaPay, subscription billing, secure checkout flows, webhook handling, and payment lifecycle logic.

    StripePayPalPaystackSasaPayWebhooks

  • Data Modeling

    PostgreSQL schemas, Prisma models, migrations, indexing, query optimization, and database access patterns that stay explainable.

    PostgreSQLPrismaDrizzleMySQLRedisMigrationsMongoDB

  • Auth & Access Control

    JWT refresh flows, HMAC-SHA256 authentication, API keys, RBAC, granular permissions, and multi-panel access boundaries.

    JWTHMAC-SHA256RBACAPI KeysRefresh Flows

  • Multi-Tenant SaaS

    Tenant-aware accounting workflows, VAT returns, staff permissions, client onboarding, subscriptions, and operational task flows.

    NestJSPostgreSQLTypeScriptPrisma

  • Real-Time Systems

    Socket.io notifications, chat, real-time product features, throttling, rate limiting, and concurrency-aware backend behavior.

    Socket.ioWebSocketsRedisNestJS

  • KYC & Compliance

    Stripe Identity, FacePhi, NameScan, Companies House API, and identity flows for fintech and regulated workflows.

    Stripe IdentityFacePhiNameScanNode.js

  • Reliability Engineering

    N+1 elimination, connection pool contention reduction, controlled retries, observability hooks, and production API documentation.

    PostgreSQLNestJSPrismaREST APIsAWS S3

  • Infrastructure & DevOps

    Container deployment, cloud storage, compute, and automated pipelines for backend services in production environments.

    AWS EC2AWS ECSAWS S3GitHub ActionsCI/CDDocker
04Featured Work

Production systems with backend weight.

01

KashyBee

Enterprise fintech backend
Production fintech

Built from scratch as the sole engineer across the full stack using NestJS, TypeScript, Prisma, and PostgreSQL for backend systems, and Next.js with React for agent, merchant, sub-agent, and admin panel interfaces covering voucher-based transactions, wallet workflows, and settlements.

  • Delivered 100+ production APIs, 75+ relational models, and feature modules across end user, agent, sub-agent, merchant, accounts, HR, and super admin panels.
  • Handled end-to-end frontend development across agent, merchant, sub-agent, and admin panels including UI architecture, API integration, and UX decisions as the only engineer on the project.
  • Implemented HMAC-SHA256 authentication, JWT refresh flows, API key management, AWS KMS wallet key encryption, and granular RBAC.
  • Improved reliability through N+1 elimination, strategic indexes, reduced connection pool contention, and 127+ database migrations.
02

OhhNFT

Web2 and Web3 marketplace backend
300K+ active users

Maintained and optimized an NFT marketplace backend spanning MySQL, Redis, raw SQL, and Web3 provider integrations across multiple chains.

  • Reduced pressure on high-traffic workflows through optimized SQL queries, indexing strategy, and backend access pattern improvements.
  • Integrated providers including Moralis, Alchemy, and Stargaze for wallet connectivity, NFT minting, and on-chain data access.
  • Built backend features for hub creation, DAO governance, raffles, quests, rewards, staking, and community workflows.
03

Pecunia

Multi-tenant SaaS accounting
UK SaaS platform

Built backend modules for a UK-focused accounting platform with tenant-aware VAT returns, staff management, client onboarding, task tracking, KYC, and billing.

  • Integrated Companies House API, Stripe Identity, and Stripe subscriptions for billing, invoicing, renewals, and payment lifecycle handling.
  • Designed role-based staff permissions, client data workflows, and backend APIs across multiple tenant contexts.
  • Kept accounting operations structured around clear data ownership, auditability, and stable API contracts.
04

Realwealtdy

Real estate marketplace backend
Marketplace systems

Built backend services for a real estate marketplace using TypeScript, NestJS, PostgreSQL, Prisma, and REST API architecture.

  • Implemented Google OAuth, Apple Auth, magic link login, authenticator app login, and role-based access control.
  • Developed property listings, auctions, inspection scheduling, calendar integration, automated email notifications, digital offers, and agreement signing.
  • Designed marketplace workflows around reliable state transitions and clear buyer, seller, agent, and admin boundaries.
05

MoneyPings

Cross-border payment infrastructure
Payments and KYC

Developed backend services for global money transfer workflows using Node.js, Express.js, MongoDB, payment gateways, KYC providers, and reconciliation logic.

  • Integrated Stripe, PayPal, Paystack, and SasaPay with transaction logging, webhook handling, and secure checkout flows.
  • Integrated identity and compliance providers including Stripe Identity, FacePhi, NameScan, and related KYC services.
  • Built payment-adjacent backend paths where correctness, traceability, and failure handling directly affect user trust.