Backend Engineering
Specialist

Building production-grade APIs, job processing systems, and fault-tolerant infrastructure.

  • Built distributed job queue with retry & DLQ
  • Implemented JWT auth with refresh rotation & rate limiting
  • Designed payment system with webhook handling
  • Optimized API performance with Redis caching
Explore Backend Systems Get in Touch
Alfarizi Profile

What I Build

Scalable APIs

High-performance RESTful services dengan rate limiting, caching, dan clean architecture.

Distributed Job Processing

Async job queues dengan retry mechanism, dead letter queues, dan horizontal scaling.

Secure Auth Systems

JWT authentication dengan refresh token rotation, RBAC, dan distributed rate limiting.

Payment & Webhook Infrastructure

Payment processing dengan circuit breaker, webhook reliability, dan subscription billing.

About Me

I am a software engineer with over 2.5 years of specialized experience in building robust backend systems. My expertise lies in designing microservices, optimizing database performance, and ensuring system reliability handling high-concurrency traffic in the fintech and logistics sectors.

Technical Arsenal

Distributed Job Processing (Go + Redis)
JWT Auth with Refresh Token Rotation
Rate Limiting (Token Bucket, Redis)
Payment & Webhook Infrastructure
Clean Architecture & Testing
Docker & Kubernetes
PostgreSQL & Redis
Go (Gin, Fiber)

Open Source Projects

Production-Grade Backend Systems on GitHub

⭐ Flagship Project

job-queue

Built a high-performance async job processing system using Go & Redis to handle distributed job distribution with retry mechanism and failure isolation.

Client
→
API Server
→
Redis QueueLPUSH/BRPOP
→
Worker Pool
→
Handler
↓
✓ Success
↓
↻ RetryZSET + Backoff
↓
✗ DLQ

Key Engineering Points

  • Redis Lists (LPUSH/BRPOP) untuk reliable job distribution
  • Exponential backoff retry (2^retries × 5s) dengan Dead Letter Queue
  • Graceful shutdown untuk zero job loss
  • Horizontally scalable (docker-compose up --scale worker=5)
Retry + DLQ Structured logging (zap) Graceful shutdown
Go Redis Docker zap
View on GitHub

saas-payment-platform

Built a full-stack payment API using Go (Fiber) + Next.js + PostgreSQL to handle subscription billing and webhook reliability with circuit breaker pattern.

Key Engineering Points

  • Circuit breaker pada webhook delivery (closed/open/half-open) + exponential backoff
  • 383 tests, 81.1% coverage
  • 7-stage CI/CD pipeline, K8s manifests
  • Redis sliding window rate limiting, HMAC webhook signatures
383 tests 81.1% coverage K8s ready 7-stage CI/CD
383 tests / 81.1% coverage Circuit breaker + retry
Go (Fiber) Next.js PostgreSQL Redis K8s
View on GitHub

shield-auth

Built a secure authentication system using Go + PostgreSQL + Redis to handle JWT rotation, distributed rate limiting, and role-based access control.

Key Engineering Points

  • JWT access + refresh token dengan rotation & revocation
  • Distributed rate limiter per user via Redis
Token rotation & revocation Distributed rate limiting
Go PostgreSQL Redis Docker
View on GitHub

feature-flag

Built a feature flag management system using Go (Gin) + PostgreSQL + Redis to handle gradual rollout with consistent hashing and sub-millisecond evaluation.

Key Engineering Points

  • Consistent hashing untuk percentage rollout (deterministic)
  • Redis caching untuk sub-millisecond flag evaluation
Sub-millisecond evaluation
Redis caching Evaluation metrics
Go (Gin) PostgreSQL Redis
View on GitHub

url-shortener

Built a URL shortener service using Go (Gin) + PostgreSQL to handle custom alias creation and click analytics with IP-based rate limiting.

Key Engineering Points

  • Custom alias + expiration support
  • Click analytics (IP, User-Agent, timestamp)
  • IP-based rate limiting
Rate limiting Auto DB migration
Go (Gin) PostgreSQL Docker
View on GitHub

mcp-tools

Built an MCP server using Go to handle multi-database observability and incident analysis with stdio + HTTP (SSE) transport.

Key Engineering Points

  • Multi-database support (PostgreSQL, MySQL)
  • Elasticsearch log analysis + Prometheus metrics
  • Incident analysis meta-tool
Audit trail Multi-transport (stdio + SSE)
Go PostgreSQL MySQL Elasticsearch Prometheus
View on GitHub

System Thinking

Designing Reliable Job Processing

Bagaimana memastikan setiap job diproses tepat satu kali, dengan retry yang aman dan failure isolation melalui Dead Letter Queue.

Handling High Traffic APIs

Strategi rate limiting, caching layer, dan connection pooling untuk menjaga latency rendah di bawah beban tinggi.

Preventing Race Conditions

Penggunaan Redis atomic operations, distributed locks, dan idempotency keys untuk menghindari data corruption pada concurrent requests.

Professional Journey

04/2025 - Present

Software Engineer

PCS Payment

  • Enterprise MDM Ecosystem (Server & Agent) Designed an enterprise-grade MDM server (Go/Gin) managing 1,000+ devices via WebSockets. Checkmated security risks with a Windows Service agent featuring WMI process monitoring, registry-based USB blocking, and VPN kill-switches.
  • Payment Middleware & Financial Protocols Architected a high-concurrency Redis-first middleware bridging gRPC to HTTP APIs. Developed a mission-critical ISO 8583 Scheduler ensuring 24/7 banking connectivity with auto-recovery logic.
  • Security & Infrastructure Implemented SSO with Keycloak, remediated all M3S vulnerabilities (Pen-test), and integrated Google Cloud Pub/Sub for event-driven resilience.
06/2023 - 04/2025

Junior Software Engineer

PCS Payment

  • Performance Engineering: Engineered a Go-based profiling service improving speed by 70% and resolved persistent database deadlocks.
  • Core Products: Developed the Merchant Management Service (M3S) for ticketing/EDC control and automated monthly reporting systems.
  • Visualization: Built actionable dashboards for operational insights.

Let's Connect

Open to opportunities in Backend Engineering and Distributed Systems.