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Available for freelance work

AmirMohammadMirzaeiRad

Backend Engineer

Mashhad, Iran · UTC+3:30

5 years designing distributed systems, scalable microservices, and high-performance APIs with TypeScript, Node.js, NestJS, and Python — now building AI-powered backends with RAG.

reel.mp4

// 01. Ethos

Systems over syntax. Architecture first.

Five years across fintech, logistics, sports management, and AI SaaS taught me one thing: software engineering isn't about the volume of syntax produced, it's about the clarity of the architecture defined. I build systems that are resilient by default, not by patch. My approach is subtractive. I start with the complexity of the problem and strip away everything non-essential until only the pure function remains. Event-driven cores, typed contracts end-to-end, databases tuned before code is blamed. This is Swiss design applied to distributed systems.

5+
Years shipping
11
Services in production
8
Skill domains
// build.log
const engineer = {
  role: "Backend Engineer",
  stack: ["TypeScript", "NestJS", "Python", "PostgreSQL", "Kafka"],
  location: "Mashhad, Iran",
  status: "Systems online",
};

// 03. Capabilities

08 Domains. One Discipline.

The full taxonomy — every domain, every tool, in the open.

Languages

4

TypeScript

Used in
UnoPay

JavaScript

Used in
No shipped project yet

Python

Used in
IPG SandboxLinkschin AggregatorKarStack

SQL

Used in
No shipped project yet

Frameworks & Runtimes

5

Node.js

Used in
UnoPay

NestJS

Used in
Novent Backend

FastAPI

Used in
IPG SandboxLinkschin AggregatorKarStack

React

Used in
Linkschin Aggregator

Next.js

Used in
IPG SandboxLinkschin AggregatorKarStack

APIs & Protocols

4

REST

Used in
No shipped project yet

GraphQL

Used in
No shipped project yet

gRPC

Used in
Novent Backend

tRPC

Used in
No shipped project yet

Databases & Caches

7

PostgreSQL

Used in
Novent Backend

SQL Server

Used in
No shipped project yet

Redis

Used in
Novent Backend

PGVector

Used in
No shipped project yet

Qdrant

Used in
No shipped project yet

Pinecone

Used in
No shipped project yet

Milvus

Used in
No shipped project yet

AI & LLMs

11

RAG

Used in
No shipped project yet

LangChain

Used in
No shipped project yet

LangGraph

Used in
No shipped project yet

Model Context Protocol

Used in
No shipped project yet

OpenAI Agents SDK

Used in
No shipped project yet

Tool Calling

Used in
No shipped project yet

Function Calling

Used in
No shipped project yet

Structured Outputs

Used in
No shipped project yet

Hybrid Search

Used in
No shipped project yet

Semantic Search

Used in
No shipped project yet

Embeddings

Used in
No shipped project yet

Messaging & Streaming

3

Apache Kafka

Used in
No shipped project yet

BullMQ

Used in
No shipped project yet

Debezium CDC

Used in
No shipped project yet

Architecture & Patterns

8

Distributed Systems

Used in
No shipped project yet

Microservices

Used in
No shipped project yet

Domain-Driven Design

Used in
No shipped project yet

CQRS

Used in
Novent Backend

Hexagonal Architecture

Used in
No shipped project yet

Event-Driven Architecture

Used in
No shipped project yet

Transactional Outbox

Used in
No shipped project yet

Clean Architecture

Used in
No shipped project yet

DevOps & Tools

11

Docker

Used in
IPG Sandbox

Kubernetes

Used in
No shipped project yet

Linux

Used in
No shipped project yet

Nginx

Used in
No shipped project yet

Git

Used in
No shipped project yet

CI/CD

Used in
No shipped project yet

MinIO (S3 Compatible)

Used in
No shipped project yet

Jest

Used in
No shipped project yet

Playwright

Used in
Linkschin Aggregator

Integration Testing

Used in
No shipped project yet

End-to-End Testing

Used in
No shipped project yet

// 02. Chronology

Career timeline

Four years of shipping systems across fintech, sports, logistics, and AI SaaS — from backend services to leading a platform end to end.

Full Stack Engineer (Solo Venture)

Oct 2025 — Feb 2026

AI Chatbot Platform (Chatterbot)

TYPESCRIPTNESTJSPYTHONFASTAPIKAFKA

Architected a production-ready multi-tenant AI SaaS platform consisting of 11 independent NestJS microservices following Domain-Driven Design (DDD), CQRS, and Hexagonal Architecture. Engineered a modular Retrieval-Augmented Generation (RAG) pipeline using FastAPI, LangChain, LangGraph, and MCP, supporting OpenAI, Anthropic, and Ollama models with Tool Calling, Structured Outputs, Hybrid Search, and Reranking. Unified frontend and backend communication through a shared TypeScript SDK using tRPC for client APIs and gRPC across 11 distributed services. Implemented an event-driven architecture using Apache Kafka, Debezium CDC, and the Transactional Outbox Pattern to maintain reliable event propagation and strong data consistency. Integrated PostgreSQL, PGVector, Qdrant, Pinecone, and Milvus to provide scalable semantic search and vector-based document retrieval. Established Docker-based development environments and Kubernetes-ready deployment workflows with CI/CD pipelines for all platform services.

Full Stack Engineer

Jul 2025 — Sep 2025

Tehran Taekwondo Association

NODE.JSNESTJSPOSTGRESQLREACTNEXT.JS

Developed the official provincial athlete management platform supporting 40,000+ registered athletes, 400+ tournaments, and approximately 1,000 coaches and referees. Created scalable registration workflows for individual, team, and group competitions, generating tournament brackets automatically for 400+ events. Delivered secure administrative dashboards providing reporting, scheduling, ticketing, and role-based access management. Digitized athlete registration and tournament administration processes, replacing manual workflows across the provincial organization.

Backend Developer

Jan 2024 — Jun 2025

Daal

NODE.JSPOSTGRESQLSQLPOSTGRES FDWDOCKER

Led the migration of 100,000+ production financial records into a redesigned PostgreSQL schema while preserving production data integrity. Optimized more than 30 SQL reports and 10 executive dashboards through indexing strategies, PostgreSQL views, query tuning, and Foreign Data Wrappers (FDW). Built PostgreSQL FDW-based cross-database reporting solutions spanning 100,000+ financial records across production databases. Collaborated within a 5-engineer Agile team to deliver backend APIs and financial services for an enterprise fintech platform.

Full Stack Engineer

Jul 2022 — Dec 2023

Parssazeh

NODE.JSSQL SERVERREACTTYPESCRIPT

Modernized legacy accounting and inventory management systems containing 1,000,000+ financial and inventory records across 5 warehouses. Refined SQL Server queries and backend services to improve reporting performance for business-critical financial operations. Delivered automated reporting pipelines processing 1M+ operational records for auditors and internal stakeholders. Replaced legacy application modules with scalable backend architecture to simplify maintenance and future development.

Backend Developer

Dec 2021 — Jun 2022

Espad

NODE.JSPOSTGRESQLREST APISDOCKER

Implemented backend services powering digital reservation, booking, and tour management workflows. Developed RESTful APIs supporting customer management, reservation processing, and scheduling operations. Optimized database queries and service architecture to improve application maintainability and backend performance. Partnered with frontend engineers to deliver production-ready features in an Agile development environment.

Business Management

2019 — 2021

University of Isfahan

BUSINESS MANAGEMENTACADEMIA

Completed two years of undergraduate coursework before leaving to pursue a full-time software engineering career.

Projects

Projects

Products, interfaces, and systems built end to end.

01/

UnoPay

Fintech & SDK

TYPESCRIPTSDKEDGEPAYMENTS
UnoPay
Overview

UnoPay solves the fragmentation and brittle integration challenges of Iranian payment gateways by providing a strongly-typed, single-entrypoint client architecture. Built entirely on standard Web Fetch primitives with zero external runtime dependencies, it runs identically in Vercel Edge, Cloudflare Workers, Node.js 18+, Bun, and Deno.

Architecture

Pluggable Adapter Pattern & Universal Fetch Runtime

The SDK centers on the UnoPay orchestrator client parameterized over configured gateway keys. Each payment provider implements a standardized GatewayAdapter interface exposing uniform createPayment and verifyCallback signatures. Provider-specific payload quirks, error codes, and currency variations are isolated inside adapters, preventing external leakage.

Highlights
  • Universal Runtime: 100% standard Fetch API compatible with Cloudflare Workers, Vercel Edge, Bun, Deno, and Node.js.
  • Strict Zero-Any Typing: Gateway identifiers and response schemas are strictly inferred and autocompleted.
  • Automatic Currency Normalization: Seamlessly handles IRR, IRT, and TOMAN conversions.
Stack
TYPESCRIPTSDKEDGEPAYMENTSNODE.JSBUNDENO
02/

IPG Sandbox

Developer Tooling & Testing

DOCKERFASTAPIPYTHONNEXT.JS
IPG Sandbox
Overview

Testing payment workflows in Iranian software development has historically required live test credentials, manual card simulations, or unstable staging endpoints. IPG Sandbox is a zero-setup, self-hosted emulation suite that mirrors the REST and SOAP APIs of major payment gateways (Zarinpal, IDPay, Behpardakht Mellat), allowing developers to test approve, decline, timeout, refund, and verify-fail scenarios deterministically in local dev and CI/CD pipelines.

Architecture

Dual-Plane Simulation Engine with Deterministic State Machine

Architected into a high-performance Python FastAPI engine and a Next.js inspection dashboard. The engine intercepts standard gateway endpoints, models transactions through a persistent state machine, and evaluates header-driven scenario rules (X-Sandbox-Scenario) without modifying production code under test.

Highlights
  • 18-Cell Scenario Matrix: 6 realistic outcomes (approve, decline, timeout, refund, pending_settle, verify_fail) across 3 gateway adapters.
  • Zero External Dependencies: Runs fully offline via Docker Compose without external internet access or credit cards.
  • Fault-Injection via Headers: Non-invasive testing without changing application business logic.
Stack
DOCKERFASTAPIPYTHONNEXT.JSTESTINGMOCK
03/

Linkschin Aggregator

Data Extraction & Streaming

NEXT.JSFASTAPIPYTHONTURBOREPOClosed source
Linkschin Aggregator
Overview

Linkschin is a high-throughput search and media aggregator designed to extract direct download links, split RAR game archives, and audio previews from complex Iranian media portals without routing media bandwidth through the server. Built as a unified Turborepo monorepo uniting a Next.js web application with an asynchronous Python FastAPI extraction engine.

Architecture

Decoupled Headless Extraction & Direct Streaming Pipeline

Designed with strict separation between link discovery and media delivery. The backend handles distributed web scraping, anti-bot bypass, archive structure parsing, and link resolution, while direct file transfers stream strictly between the client and upstream CDNs, eliminating server bandwidth bottlenecks.

Highlights
  • Zero-Proxy Bandwidth Architecture: Server processes only lightweight JSON metadata while media downloads stream directly from CDNs.
  • Multi-Part Archive Intelligence: Automatically groups split game volumes and identifies required archive passwords.
  • Turborepo Polyglot Monorepo: Orchestrates Node.js/TypeScript frontend and Python backend tooling seamlessly.
Stack
NEXT.JSFASTAPIPYTHONTURBOREPOREACTPLAYWRIGHT
04/

KarStack

Job Platform & Aggregator

NEXT.JSFASTAPIPYTHONSQLMODELClosed source
KarStack
Overview

KarStack is an end-to-end recruitment platform and career intelligence aggregator. It continuously crawls and normalizes tech job postings across Iranian hiring boards into a centralized database, offering advanced search filters (tech stack, salary range, remote status, seniority), applicant tracking, and administration tools.

Architecture

Polyglot Monorepo with Relational Ingestion Engine

Structured as a Turborepo monorepo housing a Python FastAPI REST API with SQLModel/PostgreSQL and three Next.js applications (Public Web, User Dashboard, Admin Dashboard). Shared UI design tokens, Radix UI primitives, and TypeScript types are managed in shared workspace packages.

Highlights
  • Structured Job Normalization: Unifies disparate posting formats into a clean schema with parsed skill requirements.
  • Multi-Workspace Monorepo: Single repository coordinating 3 Next.js applications and shared UI design system packages.
  • Strict Postgres Target: Built specifically for PostgreSQL 17 with psycopg3 driver for maximum query performance.
Stack
NEXT.JSFASTAPIPYTHONSQLMODELTAILWINDTURBOREPORADIX-UI
05/

Novent Backend

Enterprise Microservices

NESTJSKAFKAPOSTGRESQLREDISClosed source
Novent Backend
Overview

Novent Backend is an enterprise-grade distributed microservices platform engineered for high-concurrency event handling and financial transactions. Utilizing Hexagonal Architecture (Ports and Adapters) with Command Query Responsibility Segregation (CQRS), it decouples domain logic from external transport layers while ensuring sub-millisecond data synchronization via Apache Kafka and Debezium Change Data Capture (CDC).

Architecture

Hexagonal (Ports & Adapters) Microservices with CQRS & Event-Driven CDC

Composed of an API Gateway, Core Business Service, and Financial Service communicating via gRPC and Kafka. Database changes to PostgreSQL are streamed in real-time by Debezium into Kafka topics, where search workers ingest them into Meilisearch, maintaining eventual consistency without application-level double writes.

Highlights
  • Strict Hexagonal Architecture: Complete decoupling of Domain, Application, Infrastructure, and Presentation layers.
  • CQRS Command/Query Separation: Separates read-heavy query pipelines from write-heavy command handlers.
  • Change Data Capture (CDC): Debezium connector monitoring Postgres WAL for reliable, atomic event propagation without dual-write bugs.
Stack
NESTJSKAFKAPOSTGRESQLREDISDEBEZIUMMEILISEARCHCQRSGRPC

Articles

Notes on shipped work

Longer notes on how a system is built and the decisions behind it.

// process.log

From idea to production

Every engagement follows the same arc: understand the problem, define the boundaries, ship something that runs.

01

Discover

Map the problem space, audit the existing system, and surface the constraints before writing code.

02

Architect

Define modules, contracts, and data flow. Choose patterns that match the complexity, not the fashion.

03

Implement

Build in vertical slices. Ship one complete path end to end before widening the scope.

04

Observe

Structured logs, metrics, and health checks land with the first deploy. If it cannot be monitored, it is not done.

05

Deploy

CI/CD with reproducible environments and a rollback path that has been exercised, not assumed.

06

Iterate

Measure the result, fix the bottleneck, and pay down debt deliberately instead of accumulating it.

07

Document

Decision records and runbooks so the system survives the context of the person who built it.

RESPONSE TIME: < 24 HOURS

Get In Touch

Have an idea? Let's build it.

I'm available for backend architecture, distributed systems, and AI-enabled products. Tell me what you are building and I'll reply with a concrete plan.

TIMEZONE: UTC +3:30 (Asia/Tehran)