Incident debugger
Payment succeeds, invoice missing
Step through the failure chain from gateway webhook to database timeout.
Start
Webhook received
Razorpay delivered the payment event and the endpoint returned HTTP 200.
Open to the right engineering work
I work on backend services, payment flows, production debugging, and practical web tools. I try to keep the work clear, reliable, and useful.
Kuala Lumpur / backend-focused full stack / Java, Spring Boot, React
Live status
oakstat.us Uptime Monitoring Checking… easybin.xyz Secure Transfer Checking… lorm.pro Fake Data Toolkit Checking… uscs.sufi.my Signal Transceiver Checking… invoice.sufi.my E-Invoicing Checking…
Reachability from your browser. Each product answers within 6s or is marked down.
Focus
What I work on.
Backend services
Java, Spring Boot, REST APIs, SQLProduction debugging
GCP Logging, transaction tracingFrontend integration
React, TypeScript, API-driven UIPublic tools
Small products, docs, research05
Live products
04
Case studies
06
Articles
05
Guides
11
Browser games
01
Peer-reviewed publication
Featured Work
Selected case studies
Real systems, real problems, real outcomes.
Case Study Java · Spring Boot · GCP Logging
Payment Transaction Debugging System
Investigated missing financial transactions by tracing logs across distributed services — identified a silent database write failure in the webhook processing layer and restored affected records.
JavaSpring BootGCP LoggingSQLRazorpay
View case study
Open Source Rust · PyTorch · BERT
NeuralAV — AI Antivirus
Rust-based antivirus engine using a PyTorch fine-tuned BERT neural network for binary classification — extends my published malware-detection research into a working tool.
RustPyTorchBERTNeural NetworksBinary Analysis
View case study
Published Research Python · Neural Networks · Binary Data Analysis
AI Malware Detection
Published research on neural network-based malware detection using binary data analysis.
PythonNeural NetworksBinary Data AnalysisResearch
View case study
Open Source Rust · WebAssembly · HTTP
Rustra — Rust + Wasm Web Framework
A multi-threaded web framework written in Rust with WebAssembly, built to learn the internals of HTTP servers, thread pools, and browser-side Rust.
RustWebAssemblyHTTPConcurrency
View case study
Work in use
Small products and tools I maintain
A few public projects with their own domains. Useful, simple, and still improving.
Live product Uptime Monitoring
oakstat.us
Monitor services, publish status, and catch downtime before users do.
Public uptime monitoring with global checks, status pages, and incident visibility.
Visit product Used on a custom domain Secure Transfer
easybin.xyz
Send sensitive snippets and files without leaving copies around.
One-time encrypted text and file sharing with quick PIN handoff and automatic expiry.
Visit productlorm.pro
Fake Data Toolkit
Lorem, mock APIs, datasets, logs, and generated test payloads in one place.
uscs.sufi.my
Signal Transceiver
Browser-based ultrasonic transmit, receive, analyze, and tuning controls.
invoice.sufi.my
E-Invoicing
Invoice creation flow with payment links, QR sharing, and compliant PDF output.
Experience
Recent roles
Software Developer
DataKraf Sdn. Bhd.
- Built Java and Spring Boot REST APIs for fintech payment and invoicing flows.
- Investigated production payment issues using GCP Logging, transaction IDs, and gateway event traces.
- Supported SIT/UAT cycles and documented repeatable debugging procedures for payment-related issues.
Full Stack Developer
BJAK Sdn. Bhd.
- Built React frontend features and integrated them with backend REST APIs.
- Worked in Agile sprints, participated in code reviews, and shipped incremental releases.
- Improved maintainability by refactoring legacy UI modules and fixing production-facing bugs.
Tech Stack
Tools I ship with
Backend
04 JavaSpring BootREST APIsSQL
Frontend
04 ReactNext.jsTypeScriptJavaScript
Cloud / Tools
04 GCP LoggingGitPostmanCI/CD
Research
04 Neural NetworksBinary AnalysisAI SecurityPublication
About
I like building useful software and making systems easier to understand.
I'm Muhammad Sufi Afifi, a backend-focused full stack engineer based in Kuala Lumpur. Most of my work sits where backend services meet web applications — Java and Spring Boot APIs on one side, React interfaces on the other, and the debugging work that keeps both alive. Right now that means fintech payment flows: tracing transactions across services with GCP Logging and making sure money ends up where it should.
sufi@portfolio ~
Welcome. Try help to see commands.
Published Research
Enhancing AI Malware Detection Using Neural Network
with Binary Data Analysis
A peer-reviewed book chapter applying neural networks to binary executable analysis for malware classification — applied machine learning in a real cybersecurity context.
Published in
Atlantis Press, 2024
DOI
10.2991/978-94-6463-589-8_7
Type
Book Chapter
Engineering Notes
Writing that explains systems
Not tutorials. Explanations of how things actually work.
01
Git Workflow That Actually Works
A practical branching strategy for small teams that balances speed with safety.
Mar 15, 2026
02
REST vs GraphQL: When to Use Each
A practical comparison of REST and GraphQL with real-world trade-offs.
Feb 28, 2026
03
ELI5: Docker Containers Explained
Understanding containers, images, and why they matter for deployment.
Feb 15, 2026
Free Guides
Engineering references
Practical references for backend development, system design, and debugging.
Playground
11 browser games, no sign-up
Arcade classics, an unbeatable chess AI, and trivia — every game runs entirely in your browser.
Flappy Bird
Navigate through pipes. Classic arcade gameplay with high score tracking.
Dino Runner
Jump over obstacles in this endless runner. Speed increases over time.
Snake
The classic. Eat, grow, and don't run into yourself or the wall.
2048
Slide and combine tiles to reach 2048. Simple rules, hard to put down.
Tic-Tac-Toe
Face an unbeatable minimax AI. Best case: you force a draw.
Race Car
Dodge traffic in this top-down racer. Survive as long as you can.
Mental Math
Quick arithmetic under a countdown. No calculator allowed.
History Quiz
Well-known events, people, and places throughout history.
Encyclopedia Trivia
General knowledge on science, geography, and the natural world.
Spot It
Find the one hidden figure in a crowd before the clock runs out.
Chess
Full rules -- castling, en passant, promotion -- against a minimax AI.
Open source
Recent commits
What I'm shipping right now, straight from GitHub.
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Systems Lab
Small interactive demos
A few browser-based tools that make backend work visible: debugging, reliability, webhooks, traces, and architecture.
API reliability probe
Check public endpoints
A lightweight reachability check for the domains already on this portfolio. Cross-origin responses are measured as reachable/failed, not inspected.
oakstat.us Idle
easybin.xyz Idle
lorm.pro Idle
uscs.sufi.my Idle
invoice.sufi.my Idle
Webhook simulator
Choose a failure mode
HTTP 200 Persist transaction, publish invoice event.
Idempotency key is new, signature is valid, and persistence succeeds.
Log trace explorer
Trace by transaction ID
12:04:11.018 waiting for trace...
Architecture snapshot
Payment flow boundaries
request webhook write logs
System map
Every boundary can fail silently.
Click a node to see where things break in a real payment flow.
Spot the bug
Find the defect
A real-world code smell. Click the line you think is wrong, then read the explanation.
Pick a line to check.
Need someone who can ship the product and debug the system?
Open to roles and collaborations where shipping, reliability, and technical judgment all matter.