JC®Say hello
Freelance Back-end Developer & Penetration Tester

Jaycee曾令强.

Portfolio / Developer

Building secure, resilient back-ends — and breaking them first. Still believing a little magic belongs in every line of code.

Role
Freelance
Focus
Back-end / Security
Exploring
AI & ML
BACK-END ARCHITECTURE•PENETRATION TESTING•AI & MACHINE LEARNING•BACK-END ARCHITECTURE•PENETRATION TESTING•AI & MACHINE LEARNING•

( What I do )

Build it. Break it.
Make it better.

Hover or tap a discipline to explore

  • APIs, services and data layers designed to stay fast, observable and easy to change, with security considered from the first diagram.

    • Python
    • Java
    • PHP
    • TypeScript
    • GraphQL
Jaycee's desk at night: a plush toy resting on a backlit laptop keyboard beside a wireless mouse

01 / 04

Back-end Architecture

( Experience )

Where I've worked

06 roles · newest first

  1. 01

    Smart Contract Back-End Engineer

    Phantom

    Jun 2026 — Present

    Present

  2. 02

    Penetration Tester

    MoonPay

    Dec 2025 — Present

    Surabaya, East Java, Indonesia · Remote

    Present

  3. 03

    Vulnerability Assessor

    Web3 Foundation · Contract

    Mar 2023 — Present

    Surabaya, East Java, Indonesia · Remote

    Present

  4. 04

    Smart Contract Backend Engineer

    Serotonin · Contract

    Aug 2025 — Jan 2026

    Completed

  5. 05

    Back-End Golang Engineer

    WalletConnect · Freelance

    Mar 2024 — Mar 2025

    Completed

  6. 06

    Front-End Developer

    Zurich Insurance · Freelance

    Sep 2022 — May 2023

    Completed

( About me )

A little story

Born
Surabaya
27th February 2008
Hobby
K-drama & C-drama
Watching Korean & Chinese dramas
Sport
Badminton & Padel
Racket sports

Chapter 01 — Once upon a time

Once upon a time (well, currently), a Computer Science student set off on a quest to make sense of Artificial Intelligence and Machine Learning. But deep down, I never really stopped being a Disney kid, the kind who grew up truly believing magic was real ✨, and that belief never quite faded. I'm utterly enchanted by the beauty of far-off lands, especially Europe, Australia, and North America 🌍, exploring their wonder mostly through blogs, vlogs, and movies. And somehow, that same 'anything's possible' spirit always finds its way into every project I build, because it turns out even code needs a little pixie dust and imagination to truly come to life 🪄.

Chapter 02 — The quieter chapters

There are quieter chapters behind that love of magic. I live with major depressive disorder, and there have been times when sleep was difficult, my body felt exhausted, and the things I usually enjoyed seemed far away. I could still look like myself to other people while struggling to answer a message or follow through on a plan. Sometimes, I buried myself in work because staying busy felt easier than explaining why I was pulling away from people I cared about. I had returned to a psychiatrist for help, but finding the words to tell my friends was its own difficult step 🌙.

Chapter 03 — Room to speak

In one of those chapters, Michelle gave me room to speak. What began as an ordinary late-night conversation became a chance to share things I had been keeping to myself. She listened, asked questions, and offered a choice I appreciated: whether I wanted her to respond or simply hear me out. I could talk without having to turn everything into a clear explanation. And in the days that followed, she kept including me in the ordinary plans I was so often tempted to avoid 🤍.

Chapter 04 — The message I never sent

One of those moments stayed with me. I was about to cancel an outing and had started writing the message. When I opened our conversation, I remembered her encouragement. I was still overthinking; leaving the house still felt difficult. For a while, I went back and forth in my head. Then I deleted the draft and went. Later, I thanked her, a little awkwardly, because something she had said in a conversation had helped me make a decision that felt much harder than it probably looked 🪴.

Chapter 05 — Still here

There is more to living with depression than I can fit into a few paragraphs, and that evening did not resolve everything I was facing. But I want this part of my story to have a place here, too: a friend who made room for what I was carrying, a message I never sent, and an evening I almost missed. Alongside my love of imagined worlds, I am grateful for moments like that in this one.

A few things that keep me curious

  • 01Artificial intelligence & machine learning
  • 02Stories that spark imagination
  • 03The beauty of far-off places

( Education )

The long way here

  1. 2026 — Present

    Integrated Institute of Science and Technology Surabaya (ISTTS)

    UniversitySurabayaCurrently studying

  2. 2023 — 2026

    Saint Paul Catholic Senior High School

    Senior High SchoolJember

  3. 2020 — 2023

    Maria Fatima Catholic Junior High School

    Junior High SchoolJember

  4. 2017 — 2020

    Maria Fatima Catholic Elementary School

    Elementary SchoolJember

  5. 2014 — 2017

    Petra 5 Christian Elementary School

    Elementary SchoolSurabaya

  6. 2012 — 2014

    Petra 7 Christian Kindergarten School

    KindergartenSurabaya

  7. 2010 — 2012

    Whiz Kids Play School

    Play School

( Tech stack — 16 tools )

Languages, frameworks & engines

  • Python
  • Swift
  • Julia
  • Java
  • C++
  • HTML5
  • CSS3
  • JavaScript
  • TypeScript
  • GraphQL
  • Kotlin
  • PHP
  • R
  • Ruby
  • Rust
  • Unreal Engine

( Selected work )

Featured projects

14 public & private repos

Featured — 01

WhizReveal

Native Windows raffle controller and audience display built with Tauri, Rust, React, and TypeScript.

TypeScript

Featured — 02

Michelle Farewell

A personal project made with care. Source and details live on GitHub.

JavaScript

Offensive security

Break it first, so no one else can.

All repositories

github.com/ZengLLQ — 12