Backend Developer

NestJS 10, 3TB PostgreSQL, 2,000+ req/sec Spatial APIs, BullMQ/RabbitMQ & FinTech Ledgers

Architecting high-concurrency distributed backends, multi-tenant SaaS platforms, and enterprise microservices across Node.js, NestJS, Prisma ORM, PostgreSQL (~3TB), Redis, BullMQ, and RabbitMQ. Proven track record delivering 2,000+ req/sec spatial gateways, 18+ automated national cron pipelines, and 99.98% uptime.

01 / 08Enterprise Backend · NestJS & 3TB PostgreSQL

PRISM v3 & PRISM 360 — National Retail Distribution API

18+ automated national cron pipelines, DB_CONNECTION_LIMIT=120 & Spectra Read-Replica routing

Architected and scaled mission-critical NestJS 10 + Prisma ORM backends powering Bangladesh’s top retail and FMCG distribution ecosystem (~3TB PostgreSQL database, 875M+ rows). Engineered 18+ automated national/regional cron jobs (retailerDataSync, populateAndReduceSalesSttFromStock, nationalOneViewReportPrep), Read-Replica routing via Spectra DB_ROUTE_KEY, and Azure Cache for Redis + Blob Storage integration.

NestJS 10
PostgreSQL (~3TB)
Prisma ORM
Azure Redis & Blob
18+ Cron Pipelines

PRISM v3 & PRISM 360 — National Retail Distribution API preview

Enterprise NestJS cron pipelines, Read-Replica routing & Azure Blob/Redis integration

02 / 08High-Concurrency Spatial APIs · Barikoi

Barikoi Geospatial & Fleet Routing API Gateway

2,000+ req/sec sustained throughput across 20,000+ field agents · barikoi.com

Engineered core geospatial reverse-geocoding, multi-point routing matrix, and PostGIS R-Tree polygon containment APIs supporting JTI, Care Nutrition, and Polar BD. Integrated multi-tier Redis caching (89.4% hit rate) and PostgreSQL connection pooling to deliver 8.4ms P95 response times at 99.98% uptime.

Node.js / Express
PostGIS R-Tree
Redis L1/L2 Cache
2,000+ Req/Sec
99.98% SLA

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Barikoi Geospatial & Fleet Routing API Gateway preview

Live Barikoi API platform & PostGIS high-concurrency spatial gateway

03 / 08Multi-Tenant SaaS · Cloud POS API

Zecommerz Multi-Tenant SaaS & Zephix Cloud POS API

Custom-domain tenant isolation, <20ms barcode checkout & payment reconciliation · zecommerz.com

Built the multi-tenant e-commerce SaaS backend (zecommerz-api, zephix-api) and high-speed Cloud POS API (zephixPOS-api) supporting custom merchant domains, atomic SKU inventory locking, offline-resilient POS checkout queues (18.2ms), and idempotent SSLCommerz & bKash payment webhook reconciliation.

Multi-Tenant SaaS
Cloud POS API
Atomic Inventory
SSLCommerz / bKash
Redis Caching

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Zecommerz Multi-Tenant SaaS & Zephix Cloud POS API preview

Live Zecommerz SaaS & sub-20ms Zephix Cloud POS transaction backend

04 / 08Microservice API · Fraud Intelligence

eFraudChecker — Courier COD Fraud Scoring Engine

Real-time Pathao, Steadfast & RedX delivery history aggregation · 14ms Redis lookup

Engineered a dedicated anti-fraud microservice (efraudchecker.zephix.io) that fans out asynchronously across Pathao, Steadfast, and RedX courier APIs, caches phone reputation scores in Redis (14ms lookup), blocks duplicate/spam IP checkouts, and prevents 94.2% of fake Cash-on-Delivery parcel returns.

Microservices
Redis TTL Cache
Async Fan-Out
Anti-Fraud Scoring
Webhooks

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eFraudChecker — Courier COD Fraud Scoring Engine preview

Courier COD fraud risk scoring engine & multi-carrier webhook aggregator

05 / 08Distributed Queues · BullMQ & RabbitMQ

JobMQ & PRISM DataCrafter — Distributed Queue & ETL Hub

1,840 jobs/sec worker pools, RabbitMQ flash-sale surge buffers & 65% DB load reduction

Architected high-throughput distributed background worker systems combining BullMQ + Redis Sentinel (12.4ms P99 enqueue latency) and RabbitMQ checkout surge buffers for Cloudy BD, RS Leather BD, and PRISM DataCrafter/OneView ETL jobs—cutting peak PostgreSQL write pressure by 65% with dead-letter auto-recovery.

BullMQ & RabbitMQ
Redis Sentinel
1,840 Jobs/Sec
Dead-Letter Recovery
ETL Workers

JobMQ & PRISM DataCrafter — Distributed Queue & ETL Hub preview

Distributed BullMQ/RabbitMQ worker pools & flash-sale surge buffer telemetry

06 / 08Identity & Enterprise APIs · Swagger OpenAPI

PRISM Authenticator, HRMS & Ticketing Microservices

Argon2id SSO, JWT refresh rotation, RBAC guards, @nestjs/throttler & Swagger 3.1

Designed secure NestJS + Prisma microservices across PRISM Authenticator (central Argon2id + JWT SSO), PRISM HRMS (biometric shift sync, leave approval workflows, daily activation crons), and MT Ticketing (SLA escalations, @nestjs/throttler rate guards, Swagger OpenAPI 3.1 docs, and Jest E2E suites).

Argon2id & JWT
RBAC Guards
Swagger OpenAPI
Prisma ORM
Jest E2E

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PRISM Authenticator, HRMS & Ticketing Microservices preview

OpenAPI Swagger explorer, RBAC security guards & automated Jest E2E verification

07 / 08FinTech SaaS · Double-Entry Ledger

Mosjid Khata FinTech Ledger & Subscription Backend

ACID double-entry accounting, 2-witness cash audit & offline-sync API · mosjidkhata.com

Engineered an ACID-compliant double-entry financial ledger backend powering Mosjid Khata’s community accounting SaaS. Features idempotent offline-first collection sync, multi-witness donation denomination verification endpoints, SHA-256 fiscal audit PDF exports, and queued Bangla SMS/PDF receipts.

PostgreSQL ACID
Double-Entry Ledger
Offline Idempotency
Queue Receipts
FinTech API

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Mosjid Khata FinTech Ledger & Subscription Backend preview

Live Mosjid Khata FinTech SaaS & ACID double-entry ledger backend

08 / 08Open Source · Analytical Query Engine

fast-json-query — Zero-Dependency AST Query Engine

MongoDB-style compiled AST query engine filtering 1M+ records in 0.84ms · npmjs.com

Authored and published an open-source TypeScript AST query compiler supporting expressive MongoDB-style operators ($and, $or, $in, $regex, $elemMatch, nested dot-paths) with zero runtime dependencies. Pre-compiles predicate functions to scan 1,000,000+ JSON objects in 0.84ms.

TypeScript AST
0.84ms / 1M Rows
Zero Dependencies
NPM Package
Vitest 100%

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fast-json-query — Zero-Dependency AST Query Engine preview

Published NPM package, AST compiler pipeline & 1M-record benchmark suite