OLX Indonesia – Backend Microservices

At OLX Indonesia, I worked on building and scaling high-performance microservices that power one of the largest online marketplaces in Southeast Asia.
The platform handles millions of daily users, real-time listings, chats, notifications, payments, and search traffic — requiring highly scalable, resilient, and low-latency backend systems.

I contributed to core backend services, system re-architecture, and performance optimization across multiple domains of the OLX Indonesia ecosystem.

Description

My primary responsibilities included:

  • Re-architecting existing monolith components into microservices
  • Building and maintaining critical customer-facing services
  • Improving system performance, resilience, & scalability
  • Optimizing API latency, DB queries, caching layers
  • Strengthening the observability stack (logs, metrics, traces)
  • Designing new end-to-end workflows for product & operations teams
  • Ensuring high availability during peak traffic events

The services were designed to handle millions of concurrent requests, and were deployed across a fully containerized and monitored infrastructure.

Key Projects & Capabilities Delivered

1. Ad Listings Service

  • High-throughput service powering all product listings
  • Query optimization & pagination improvements
  • Caching with Redis to reduce DB load by 40%
  • Improved SLA for listing creation & updates

2. Chat & Conversation Service

  • Real-time chat service used by millions of buyers/sellers
  • Kafka-based asynchronous message processing
  • Delivery status, read receipts, user presence
  • Latency optimizations for mobile low-network zones

3. User Profile & Authentication

  • Secure session handling with JWT
  • Rate limiting & fraud detection workflows
  • Profile metadata service with fast lookups
  • Multi-device sync + session refresh improvements

4. Notifications Microservice

  • Push notifications (FCM + in-app)
  • Event-driven architecture with Kafka
  • Delivery analytics + retry mechanism
  • Reduced notification lag from seconds → milliseconds

5. Payments & Transaction Workflows

  • Integrated multiple payment partners
  • Wallet, COD, prepaid flows
  • Reconciliation microservice
  • Strong validation + idempotent APIs

Technology Stack

  • Backend Languages: Java, Kotlin
  • Framework: Spring Boot, Micronaut (optional)
  • Databases: MySQL (transactional), MongoDB (documents)
  • Caching: Redis, Hazelcast (optional)
  • Messaging: Kafka for async workflows & event streams
  • Infra: Docker, Kubernetes, Helm
  • Cloud: AWS (EC2, EKS, S3, SNS/SQS, CloudWatch)
  • Monitoring: Grafana, Prometheus, ELK Stack
  • Other:
    • Circuit breakers (Resilience4j)
    • Centralized config service
    • API Gateway + rate limiting
    • Canary deployments & blue/green releases

Setting Up the Project (Generic Microservice Template)

```bash git clone https://github.com/rohitshakya cd olx-microservice/ ./gradlew build