Portrait of Evan
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Hi, I'm
Portrait of Evan
EvananAndroid mascotSoftware engineerfromYogyakarta, IndonesiaIndonesiaBlending engineering rigor with product instinct.

1.5+ years shipping production Android for Indomaret — a Compose POS headed for 24,351 stores and field apps used across the chain. Also Solidity contracts, applied ML, and a published ResNet-50 paper.

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24,351 stores
phased POS rollout · Indomaret
225M+ transactions
every month, 5-person mobile team
97.8% accuracy
batik classification · AITI 2026

Projects

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3 selected · 2026

Gambit

2026

Celo MiniPay chess — backend & on-chain payouts

25 / 61 commits in a three-person team

Case study

What I do

Three things I do well.

Production Android first, with smart contracts and applied machine learning close behind. I like shipping things that hold up under real store traffic.

Work with me
01

Android engineering

Kotlin and Jetpack Compose in production, a POS for Indomaret store tablets, plus three field-operations apps used across the chain. Clean Architecture, MVVM, Hilt, Room and Flows.

  • Kotlin
  • Jetpack Compose
  • Hilt
  • Room
  • Coroutines / Flow
  • Retrofit
02

Web3 & smart contracts

Solidity contracts and TypeScript SDKs for payment rails and on-chain agents. Foundry and Hardhat test suites, escrow logic, wallet integrations, and agent workflows.

  • Solidity
  • Foundry
  • Hardhat
  • TypeScript
  • Move
03

Applied machine learning

Fine-tuning vision models and shipping them as usable tools, from dataset curation and evaluation to a published ResNet-50 benchmark for Keraton batik motifs.

  • TensorFlow
  • Keras
  • Python
  • ResNet-50
  • Computer vision

Experience

Download CV

Mar 2025 — Present

Android Developer

PT Indomarco Prismatama (Indomaret) · Yogyakarta

Mar 2025 — Present

  • Building checkout, payment and authorization features for a Kotlin/Compose POS planned for phased rollout across 24,351 stores handling 225M+ transactions per month, in a five-person mobile team.

  • Shipped three field-operations apps now used across all Indomaret stores: a Compose QR-document app, a queue-display app pairing tablets over WiFi with real-time WebSocket updates, and an alarm-monitoring client.

  • Migrated transaction data from local Room tables to OWIN REST calls, making the backend the single source of truth.

  • Contributing to the store-reporting and anti-fraud reporting apps; runs UAT for owned modules and ships fixes driven by store-operations feedback.

24,351
stores in rollout
225M+
transactions / month
3
field apps shipped
5
person mobile team

Web3 & Automation Developer

DEKSA · Yogyakarta

Freelance · Yogyakarta · Dec 2024 — Aug 2025

  • Wrote Solidity smart contracts (Foundry, Hardhat) and REST backends for a crypto wallet and an animal-donation platform.

  • Automated social-media publishing in Make.com for Keraton Surakarta.

  • Solidity
  • Foundry
  • Hardhat
  • REST

Teaching Assistant

Universitas Kristen Duta Wacana · Yogyakarta

Yogyakarta · 2023 — 2024

  • Assisted students in Android Programming, Web Programming, OOP and Algorithms labs.

  • Teaching
  • Android
  • Algorithms

Publication

Published research.

Fine-tuning a ResNet-50 to classify four Keraton batik motif classes — 97.8% test accuracy, published in AITI volume 23.

All writing

Skills and education

Toolbox

What I reach for, day to day.

ANDROID

  • Kotlin
  • Jetpack Compose
  • Hilt
  • Room
  • Coroutines / Flow
  • MVVM
  • Clean Architecture
  • Retrofit

LANGUAGES

  • Java
  • TypeScript
  • SQL
  • Python

WEB3

  • Solidity
  • Foundry
  • Hardhat
  • Move

TOOLS

  • Git
  • GitHub
  • Gradle
  • Postman
  • Docker
  • Make.com

Education

GPA 3.80 / 4.00

Bachelor of Computer Science (Informatics)

Universitas Kristen Duta Wacana · Yogyakarta

Graduated Jan 2025 · completed in 3.4 years

  • TensorFlow Developer Certificate2024
  • Bangkit Academy — Machine Learning2024

Languages

  • IndonesianNative
  • EnglishProfessional

Got questions?

The short version of what I do, how I work, and how to reach me.

What Android work are you doing right now?

Checkout, payment and authorization features for an Indomaret POS built in Kotlin and Compose, planned for phased rollout across 24,351 stores. Alongside it I ship field-operations apps — QR documents, WiFi-paired queue displays streaming over WebSocket, and alarm monitoring.

Do you take on smart-contract work?

Yes. I write Solidity with Foundry and Hardhat, and I have shipped escrow contracts plus a TypeScript SDK for an x402 payment rail on Mantle. I am comfortable with on-chain payouts, registries, and agent workflows.

What's the story behind the batik paper?

It started as a final-year research project, fine-tuning ResNet-50 on four Keraton batik motif classes. The model reached 97.8% test accuracy, and the paper was published in AITI volume 23.

How do I get in touch?

Email stefaronbs@gmail.com or message +62 813-9221-2950. I am based in Yogyakarta and open to Android roles, contract work, and collaborations.