Backend Software Engineer

Hi, I'm Harry.

I build quiet systems

that keep running.

Hello! I'm Harry, a backend software engineer based in Jakarta. Since 2016 I've built and maintained systems across quite different worlds — a university platform, fintech lending, an ed-tech startup, a national government program, and now IoT air-quality monitoring.

Most of my day-to-day work is in Go, with PHP and Node.js/TypeScript along the way: REST and gRPC services, relational databases, message queues, and cloud infrastructure. A big part of the job has been the unglamorous side — production support, on-call, observability, testing, and modernizing legacy systems one slice at a time.

View My Work Experience
Harry Chang
SCROLL TO TRACE THE SYSTEM
01 — EXPERIENCE

A trail of teams, problems, and the things I learned to leave behind.

Mar 2025 - Present
Nafas Air Quality Solutions

Backend Software Engineer

Nafas Air Quality Solutions

MQTT · TELEMETRY · IoT MESH
  • · Build and maintain components of a billing, subscription, and payment management system supporting scheduled payment collection — backend services in Go, billing interface with Next.js and React.
  • · Developed an NSQ-based worker pipeline that processes roughly 100,000 air-quality sensor telemetry records per day and forwards them to BigQuery for analytics.
  • · Implemented MQTT-based backend capabilities for two-way communication and remote commands between the platform and connected IoT devices.
  • · Contribute to the gradual decomposition of a legacy monolith by building new Go services and improving the maintainability of existing components.
Jul 2023 - Dec 2024
Coordinating Ministry for Economic Affairs - Prakerja

Senior Software Engineer

Coordinating Ministry for Economic Affairs - Prakerja

API GATEWAY · ID · 18.4M USERS
  • · Developed backend features for identity verification and registration workflows supporting more than 10,000 daily registrations, on a platform with approximately 18.4 million registered users.
  • · Implemented integrations that let users view and apply for jobs through the platform, which carried around 35,000 active job listings per month.
  • · Worked on learning-partner integrations across more than 30 external partner APIs and contributed to the platform's Open API services.
  • · Supported remediation work identified through penetration testing and security reviews, including backend fixes aligned with ISO 27001 requirements and OWASP API security practices.
Nov 2021 - Jun 2023
Kuncie - EdTech

Backend Software Engineer

Kuncie - EdTech

PAYMENT FLOW · CONTENT DELIVERY
  • · Developed backend features for content management, user onboarding, video experiences, and gamification on an education platform serving more than 30,000 monthly active users.
  • · Implemented payment and subscription workflows for premium content access.
  • · Added and maintained unit tests for legacy services, increasing coverage in the areas under the team's ownership.
  • · Evaluated technologies and contributed technical input for potential adoption across engineering teams.
Jan 2019 - Oct 2021
OVO - Grab

Software Engineer → Senior Software Engineer

OVO - Grab

LENDING ORIGINATION · MICROSERVICES
  • · Developed and maintained loan origination and loan management services — onboarding consumers and business partners, repayment tracking, and outstanding-balance management.
  • · Contributed to the migration of lending data and workflows from a monolithic system to microservices, covering approximately 10 million loan transactions and 1 million users.
  • · Refactored legacy code, applied Domain-Driven Design and dependency-injection patterns where they fit, and expanded unit-test coverage for selected modules.
  • · Integrated Datadog and New Relic monitoring for service health visibility, and configured Kong API Gateway routes for public-facing endpoints.
  • · Participated in on-call rotations, investigated production incidents, and documented root-cause analyses.
Mar 2016 - Dec 2018
IT Division - Binus University

Software Engineer

IT Division - Binus University

UNIVERSITY PLATFORM · LEGACY SYSTEMS
  • · Progressed from part-time to full-time software engineer while developing features for the Binusmaya 5 web platform.
  • · Built web APIs with PHP CodeIgniter and contributed an Arduino-connected web client for an IoT smart-refrigerator research project.
  • · Maintained modules for enrichment programs, registration, student-service helpdesk workflows, exam scheduling, monitoring, and attendance.
  • · Collaborated with other engineers to plan, implement, and support university web-application features.
02 — PROJECTS

Things I shipped, mostly because someone needed them working on Monday.

A selection of products I helped build and keep running over the years — every one of them a team effort.

IDXplore Dashboard
RAW MARKET DATA →PYTHON ETL →TECHNICAL INDICATORS →SCREENING ENGINE →BUN API →DASHBOARD
FEATURED · 2025

IDXplore - Stock Analysis Platform

Python ETL · Bun/TypeScript · Next.js · TiDB

A stock analysis platform for the Indonesia Stock Exchange (IDX) covering 150+ tickers. I built the Python ETL pipeline that ingests daily market data and computes technical indicators (RSI, ADX, moving averages, Fibonacci, Bollinger Bands), the Bun/TypeScript backend API serving pre-computed screening results and fundamental data, and the Next.js frontend dashboard with a visual query builder, market screeners, and portfolio tracking. Deployed on Vercel with serverless TiDB MySQL.

VIEW SYSTEM
03 — SYSTEMS

The systems I work with.

Technologies and tools I use to build scalable applications.

Languages

  • Go
  • TypeScript
  • Python
  • Java
  • C++

Services

  • REST
  • gRPC
  • MQTT

Data

  • PostgreSQL
  • MySQL
  • Redis
  • MongoDB
  • Elasticsearch

Messaging

  • Kafka
  • NSQ
  • RabbitMQ

Infrastructure

  • Docker
  • Kubernetes
  • AWS
  • GCP
  • AliCloud

AI Engineering

  • Codex
  • Claude Code
  • OpenCode
  • Mastra
  • OpenAI-compatible SDKs