hi, my name is

Rizky Romadon

I write field notes on backend systems — the kind you only learn from real client work.

Freelance backend engineer · open to good problems

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Java · Spring Boot · DevOps · System design · AI workflows

Rizky Romadon
that's me

What's up

I'm a backend engineer who gets a little too excited about Java, Spring Boot and the unglamorous parts of production. I write down what broke, what fixed it, and what I'd do differently next time.

  • Java & Spring Boot
  • DevOps
  • System design
  • AI workflows
More about me

things I've built

Products

Besides writing, I ship software. Palang is open source; PadelClub is a license-to-use app template.

Open-source library

Palang

Stop double charges before they happen.

Duplicate request suppression for Spring Boot. A user taps “Pay” twice, a flaky network retries, a webhook is redelivered — Palang makes the second request return the first one's response instead of running again.

  • Idempotent requests with byte-identical response replay
  • Memory or Redis store; Redis claims a key with a Lua script, not SETNX-then-GET
  • Optional request-rate limiting, wrapping Bucket4j
  • A Go sibling for net/http: palang-go
  • Apache-2.0
  • Java 21 · Spring Boot 3.3+
  • On Maven Central · v0.4.0
View on GitHubpalang-goDetails
White-label source code

PadelClub

A white-label app for padel & tennis clubs.

Complete source-code template for a club app: court booking, open play, membership, tournaments, coaches and match history. A React Native mobile app on a real Spring Boot backend — rebrand it for a client in about 30 minutes.

  • Booking, open play, matchmaking, tournaments, coaches, memberships
  • React Native + Expo mobile app, Spring Boot + PostgreSQL + JWT backend
  • Rebrand from one theme file: name, colours, currency, contact
  • Docs for players, developers, backend and branding
  • Commercial license
  • Unlimited club deployments
  • iOS + Android + Spring Boot API
Get it on GumroadAsk a questionDetails
PadelClub home screen with next match and open matches
PadelClub venue page with day, hour and court picker
PadelClub open play tab

explore my work!

Featured writing

Postmortems, playbooks and notes — a few pieces I'd point a teammate to first.

All posts
How I Structure a Next.js and MDX Personal Blog cover
Latest

How I Structure a Next.js and MDX Personal Blog

A code-backed tour of how this blog turns MDX files into article routes, metadata, discovery pages, RSS, and a reviewable publishing workflow.

Next.js9 min read
System Design for Small Products cover
Post 02

System Design for Small Products

A decision framework for designing small products around real workflows, data risk, team capacity, and evidence for adding complexity.

System Design10 min read
RAG vs Fine-Tuning for Business Data cover
Post 03

RAG vs Fine-Tuning for Business Data

A practical framework for choosing RAG, fine-tuning, SQL, or a hybrid architecture when building AI features around business data.

AI18 min read
Java and Spring Boot Production Checklist cover
Post 04

Java and Spring Boot Production Checklist

A risk-based Spring Boot go-live review covering configuration, APIs, transactions, dependencies, observability, security, and recovery.

Java10 min read
DevOps Release Habits for Small Teams cover
Post 05

DevOps Release Habits for Small Teams

A lightweight release operating model for small teams: one artifact, explicit risk, observable rollout, and recovery prepared before deployment.

DevOps9 min read
Building Calm Backend Systems cover
Post 06

Building Calm Backend Systems

A workflow-level method for making backend state, failures, observability, recovery, and ownership understandable under production pressure.

Backend10 min read
My Practical AI-Assisted Engineering Workflow cover
Post 07

My Practical AI-Assisted Engineering Workflow

The review loops, context boundaries, and verification habits I use to make AI useful without giving up engineering judgment.

AI10 min read

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Topics

Let's talk

Got a backend problem, a project, or just want to say hi? Send it over.

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