MUTTAQINMUZAKKIR
Recently Shipped
Envelope Encryption System securing financial data at Aiccountant
Real-time Gmail Sync via Pub/Sub (5min → 30sec TTFV)
CI/CD Pipeline with GitHub Actions & Cloudflare Workers
Tech Stack
CASE STUDIES
Stories from the places I've been. The bugs that humbled me, the systems that taught me, and the lessons I carry forward.
THE CONTEXT
Aiccountant was an AI-powered bookkeeping platform that helped small businesses automate their financial tracking. Think of it as an intelligent assistant that reads your receipts, categorizes transactions, and syncs with your email to catch invoices you might have missed.
I joined as a software engineer to build the core infrastructure—the parts that needed to be bulletproof because they dealt with people's financial data. No pressure, right?
THE SILENT TRUNCATION
We needed to encrypt all existing financial data in production—bank accounts, transactions, sensitive PII. Zero downtime. No data loss. I designed an envelope encryption system with DEK/KEK rotation and built a type-safe backfill framework to migrate everything safely.
The migration ran smoothly in staging. Then in production, something felt off. The numbers didn't add up.
The Bug
Supabase was silently truncating our queries at 1000 rows. No error. No warning. Just... stopping. We were encrypting 1000 records and calling it a day, leaving thousands of sensitive records in plaintext.
I caught it during the integrity checks I'd built into the backfill framework. Added pagination, re-ran the migration, verified every single record. The framework's type-safety meant we could trust the results. But I still remember that cold feeling when I first saw the mismatch in the counts.
THE 7-DAY MYSTERY
Users connect their Gmail to automatically import invoice emails. Our initial implementation polled every 5 minutes—wasteful, slow, and burning through API quota. I rebuilt it with Google Pub/Sub for instant notifications.
It worked beautifully. For exactly 7 days.
The Gotcha
Gmail watch subscriptions expire after 7 days. It's in the docs, but buried. Users would connect their email, everything would work, and then a week later—silence. No new emails coming in. No errors logged. Just silence.
The fix was Trigger.dev scheduled tasks that renew watches before expiration. Simple in hindsight. But it taught me that "it works" isn't the same as "it keeps working." I now think about time-based edge cases in every system I build.
THE MISTAKE THAT TAUGHT ME
Early on, I shipped a feature without writing comprehensive tests. The logic seemed straightforward, the deadline was tight, and I convinced myself I'd add them later. "Later" never came, and three weeks in, a subtle bug in that exact code caused incorrect transaction categorization for a handful of users.
The bug itself was minor—easily fixed once found. But the feeling of knowing it could have been prevented? That stuck with me.
"Tests aren't about proving your code works. They're about proving it still works after the next person touches it—including future you who forgot why that edge case matters."
REFLECTIONS
What I'd do differently
More integration tests from day one. Unit tests catch logic errors, but integration tests catch the Supabase-silently-truncates-your-data kind of errors. The ones that only show up when systems talk to each other.
What I'm proud of
The encryption backfill framework. It's boring infrastructure—no one sees it, no one praises it. But it meant we could run migrations confidently, verify integrity automatically, and sleep at night knowing user data was protected. Good infrastructure is invisible.
What I learned
Production systems humble you. You can plan, test, and review, but something will still surprise you. The goal isn't to prevent all bugs—it's to build systems that catch them quickly and fail loudly instead of silently.
ABOUT ME
I'm a Software Engineer and Information Systems student at Universitas Indonesia, currently building production systems at Aiccountant. My work focuses on backend infrastructure, security engineering, and event-driven architectures.
At Aiccountant, I've shipped envelope encryption systems securing sensitive financial data, real-time pub/sub architectures processing Gmail sync events, and built webhook infrastructure handling payment notifications. I work primarily with TypeScript, Node.js, PostgreSQL, and Redis.
Beyond backend work, I analyze user behavior with PostHog, optimize database queries, and design systems that scale. I'm constantly learning—currently exploring machine learning and how it can enhance product intelligence.
Full-Stack Development
Data Analysis
System Design
FEATURED PROJECTS
Seedlink
Designed a comprehensive product strategy for Seedlink, an innovative platform aimed at solving co-founder compatibility challenges in Indonesia. This involved crafting a detailed Product Requirements Document (PRD), developing a growth-oriented roadmap, and outlining a Go-to-Market (GTM) plan, all aligned with key performance indicators like CTR, CAC, and LTV to ensure market fit and potential for scale.
RagaRaga
Spearheaded the product discovery phase for RagaRaga, an app designed to revolutionize skill-matching scrims for sports enthusiasts. Through rigorous customer interviews and extensive market surveys, I validated the core problem, identified key user needs, and shaped the initial product concept to ensure strong market resonance.
PetaSehat Nusantara
Pioneered the development of PetaSehat, an AI-powered RAG solution tackling Indonesia's complex regulatory hurdles for hospital construction. My role involved shaping the product vision, validating the significant market opportunity, and crafting a compelling business proposal that earned a spot in the hackathon finals.
WORK EXPERIENCE
Software Engineer
Intern
Aiccountant
Built client-side decryption for offline-first PWA, integrated real-time Gmail sync into Cloudflare edge infrastructure, and shipped end-to-end features including referral systems and bulk transaction editing.
Software Engineer
Contributor
Universitas Indonesia | Game-Based Assessment Research Team
Built full-stack research platform processing 3,000+ participants across game-based psychological assessments, with real-time monitoring for 100+ concurrent sessions.
Software Engineer (AI/ML)
Intern
PT Hiff Akvira Indonesia
Built multi-stage AI pipeline for trademark extraction from PDFs and delivered trademark similarity analysis tool using Gemini API with FastAPI and React.
Software Engineer
Contract
National Ministry of Labour
Built data ingestion and transformation pipeline in Django for national labor stress survey data, containerized with Docker for streamlined deployment.
LEADERSHIP & COMMUNITY
Project Lead
Open House Fasilkom UI 2024
Directed a 165+ person team for a major faculty open house, successfully accommodating 800 offline attendees. Optimized project workflows via Notion and Google Sheets, achieving 30% faster execution and a 90% participant satisfaction rate.
Software Engineer
RISTEK Fasilkom UI
Developed web applications and contributed to technical projects at the Faculty of Computer Science's premier IT student organization.
Other Organizations
MY TOOLKIT
Engineering
Data & Analysis
Product
LET'S CONNECT
Got an idea, project, or just want to chat? I'm always open to new opportunities and conversations.