RezaJuliandri

Senior Backend Engineer / backend · automation · machine learning

I build the half of the product nobody sees: request handling, database schemas, background jobs, and integrations that have to stay correct on the worst day of the month. Nine years of it, now as senior backend engineer on fraud and trust infrastructure at Kredibel, and tech lead of Tunelab on the side.

./view-work↓ ./say-hello→

rezajuliandri.my.id/api ·

curl -s https://rezajuliandri.my.id/me

currently: Kredibel · Tunelab · Anadex
based in: Tangerang, ID
shipping since: 2017 · 9+ yrs
writes: PHP · TypeScript · Swift

01about

The unglamorous half of the product.

Nobody opens an app to admire a well-normalised schema. They open it because the thing loaded, the number was right, and the request they sent last night actually went through.

Reza Juliandri — reza juliandritangerang, id

I work on the parts of software most users never see but rely on every day: REST APIs, automation pipelines, database performance, and the glue that keeps data flowing reliably between services.

I've been at Kredibel since 2018, working on fraud and online trust for an audience in the millions. I started part-time as a software engineer and I'm now senior backend engineer. Most of my time goes to relational data modelling, API design, query and index tuning, auth and token handling, and drawing boundaries between systems so that one team's bad day doesn't become everyone's.

Since late 2025 I've also been co-founder and tech lead at Tunelab, building Nada, which is where I get to own the whole stack: a provider-agnostic sync layer, and the analytics, email, and content infrastructure behind it, all running on Cloudflare Workers. Along the way I've interned on the financial services team at Traveloka and built an English assessment platform for the Indonesian civil aviation academy at Arxist.

I also teach, across three programs: Bangkit Academy, a joint program from Google, GoTo, and Traveloka, plus Tempa and Asah, both led by Dicoding. Well over a hundred students in mobile and backend development so far, which is the fastest way I know to find out whether you actually understand something.

based in: Tangerang,
Indonesia
focus: Backend
Automation
Machine learning
writes: PHP
TypeScript
Swift
experience: 9+ years
since 2017

02systems

How I usually build.

Two shapes I keep coming back to. One sits on servers behind Nginx, with Laravel doing the work and PostgreSQL and Redis behind it. The other lives entirely on Cloudflare's edge. Different tools, same job.

fig. 01 · the server-side shape scroll horizontally on small screens →

fig. 02 · the edge shape scroll horizontally on small screens →

01Loose coupling

Every API gets built as decoupled as I can manage. Some land on a clean architecture, others on a plain layered one, but a controller never learns how the data is stored.

02Migrations

Schema changes land next to live feature work, so every one ships with a migration strategy and a cutover safeguard. Normalising profile and watchlist data meant reshaping tables without asking the team to stop.

03Auth & errors

The failure path gets the same care as the happy path. JWT handling, refresh token rotation, and masked errors, so that a stack trace never turns into a disclosure.

04Coverage

Controller tests and 80%+ automated coverage are not a badge; they are what makes shipping continuously survivable. Regressions should be caught by the suite, not by users.

02.1code

What I mean by clean.

Not a style guide about brace placement. A standard about cognitive load: one responsibility per function, one level of abstraction, and nothing left for the person reading it in six months to hold in their head. Same rules in review as in my own branches.

before 5 levels deep · does five things

public function handle($request)
{
    if ($request->has('email')) {
        $user = User::where('email', $request->email)->first();
        if ($user) {
            if ($user->status === 'active') {
                $rows = [];
                foreach ($user->accounts as $account) {
                    if ($account->verified_at !== null) {
                        $rows[] = ['id' => $account->id];
                    }
                }
                return response()->json($rows);
            }
        }
    }

    return response()->json(['error' => 'not found'], 404);
}

after 1 level · needs no comment

public function verifiedAccounts(Request $request): JsonResponse
{
    $user = $this->users->activeByEmail($request->email);

    if (! $user) {
        return $this->accountNotFound();
    }

    return response()->json(
        $this->accounts->verifiedFor($user)
    );
}

abstraction: One level per function. A function says what happens; the ones it calls say how. No reader should have to change altitude mid-function.
length: Under 20 lines. Past 30 it is not a long function, it is several functions sharing a name.
nesting: One level preferred, 3 is the ceiling. Guard clauses and early returns instead of an if/else staircase.
naming: Names carry intent. No handle, process, manager, util, and no abbreviations that save four characters and cost a lookup.
conditionals: A boolean expression nobody can read becomes a function with a name that reads. if (shouldRetryRequest($response)), not four operators in a row.
comments: A comment explaining what the code does is a naming bug. Comments earn their place only for rationale, constraints, and decisions the code cannot state.
dependencies: They point inward. Domain logic never reaches out to infrastructure; transport, persistence, and presentation stay on their own side of the line.
the test: A top-level function should be understandable in 15 seconds without opening a single helper. If it is not, I extract before I ship.

03work

Selected projects.

Backend work photographs badly, so the screenshots are the least interesting part; the stack and the shape underneath each one are the point. Click any image to enlarge it.

Kredibel

↗

A fraud and trust platform helping Indonesian consumers avoid scams, and helping businesses onboard verified users in line with regulation.

platform totals, published on kredibel.com

scam reports: 283,099+
blacklisted: 177,910+
losses since 2018: Rp424.6B+

role: Senior Backend Engineer
years: 2018 – present
scope: API design · query & index tuning · internal apps · integrations

mobile · internal · web ─▶ nginx ─┬─▶ laravel ─▶ postgresql · redis └─▶ flask · scraping

LaravelLumenPostgreSQL PythonFlask RedisNginxFilament

Nada by Tunelab

↗

The product I co-founded and lead the engineering for: composing music by humming. The sync layer is provider-agnostic by design, with remote sync interfaces, cursor-based state, an offline queue, and conflict snapshots, all running on our own Cloudflare Workers backend.

product totals to date

registered: 1,043
paid: 30+
projects: 2,000+
tracks: 3,800+

role: Co-Founder · Tech Lead
years: Nov 2025 – present
scope: Sync architecture · analytics · email & content infra

ios (swiftui) ─▶ worker (hono) ─┬─▶ D1 · KV └─▶ R2 · Queues · Email

SwiftUIHono Cloudflare WorkersD1KV R2QueuesEmail ReactRevenueCat

Anadex

↗

A companion app for arcade trading card collectors: catalogue what you own, scan a barcode to log it, and keep a record of every session. Built and shipped alone, from the Cloudflare backend to the Android client, with a payment gateway live in production on an approved merchant account.

product totals, two months in

users: 191
active 7d: 15
cards catalogued: 1,461
scans: 419

role: Founder · sole engineer
years: Jun 2026 – present
scope: Sequence alignment · barcode scanning · live payments · Android client

web · android ─▶ worker (hono) ─┬─▶ D1 · R2 └─▶ oauth · payments

Cloudflare WorkersHonoKotlin D1R2React Jetpack ComposeML KitCameraXDuitku

English Electronic Assessment

An assessment platform for Politeknik Penerbangan Indonesia Curug, digitising placement and evaluation of English proficiency for cadets.

role: Software Engineer @ Arxist
years: 2020 – 2021
scope: Laravel backend · front-end integration

vue client ─▶ laravel api ─▶ database

LaravelVue.js

Amegu · Pet Adoption

↗

A final project connecting pet owners with adopters. One API serving two very different clients, which is where most of the interesting decisions lived.

role: Full-stack
scope: REST API · web client · Android app

nuxt web ─┐ ├─▶ laravel rest api android ─┘

LaravelNuxtJSAndroid

Clinic Web App

A clinic management tool for the Inspectorate General of Indonesia's Ministry of Education & Culture, covering medical records, lab tests, and medication inventory in one place.

role: Full-stack
domain: Records · lab results · inventory

server-rendered app ─▶ laravel ─▶ database

LaravelBootstrap

Vee · Vehicle Management

↗

Bangkit Academy 2022 capstone, built with Machine Learning and Cloud Computing students. Selected among the top 53 projects across the cohort.

role: Mobile (Kotlin)
team: Mobile + ML + Cloud Computing
result: Top 53 capstone, cohort-wide

KotlinMachine LearningGoogle Cloud

Where I've worked.

Production systems, and the classrooms that kept me honest about how they work.

Aug 2018 – Present

8 yrs · 5 roles
Kredibelcurrent

PT. Kredibel Teknologi Indonesia · Remote
1. Senior Backend Engineer full-time Feb 2026 – Present
  - Design and evolve relational data models in PostgreSQL for profile and watchlist normalisation, including migration strategy and cutover safeguards.
  - Refactor the Laravel backend around clearer service and DTO layers, and expand controller test coverage to hold regressions down under continuous delivery.
  - Harden auth: JWT best practices, refresh token handling, and secure error masking so failures don't leak anything sensitive.
  - Modernise internal Python services: Python 3.13 and Docker-based containerisation for consistent dev and deploy environments.
2. Backend Engineer contract Feb 2025 – Feb 2026
3. Backend Engineer full-time Jan 2023 – Feb 2025
  - Owned the API surface for the business and mobile products, working alongside the frontend and mobile teams.
  - Kept 80%+ automated test coverage on backend code while shipping new features.
  - Monitored and improved performance and security of backend systems continuously.
4. Back End Engineer part-time Apr 2022 – Aug 2022
  - Ran the Business API and Mobile API on a customised Lumen setup that made day-to-day development faster.
5. Software Engineer part-time Aug 2018 – Apr 2022
  - Built the APIs behind the mobile and web apps, standardising responses against Google and Facebook API conventions.
  - Migrated a legacy application onto a current Laravel version.
  - Built the billing and payment system for Kredibel Business and Enterprise, and owned the Business database structure.
Nov 2025 – Present

10 mos
Co-Founder · Tech Leadcurrent

Tunelab
- Architected a provider-agnostic sync foundation (remote sync interfaces, cursor-based sync state, offline queue handling, and conflict resolution snapshots) running on our own Cloudflare Workers backend.
- Built the internal analytics dashboard on Hono, Cloudflare D1, and React (Vite), pulling product and growth data into one place.
- Built email campaign infrastructure on Cloudflare Email, Queues, and D1, with unsubscribe routing and subscription deduplication.
- Fixed RevenueCat event duplication and stale dashboard state to keep subscription reporting consistent per user.
- Built markdown-based content tooling on Hono, Cloudflare R2, and React: media uploads, CDN browsing, image compression, soft-delete/restore.
Jun 2026 – Present

2 mos
Founder · Sole Engineercurrent

Anadex · NgideIn
- Shipped the whole product alone: a Hono API and a React SPA served by a single Cloudflare Worker, plus a Kotlin and Jetpack Compose Android client.
- Designed a sequence-alignment engine that works out which physical deck a machine is running from a short run of scanned barcodes, in either scanning direction, and drops that lock again once the machine is restocked mid-session.
- Scanning prefers the browser's own BarcodeDetector and lazy-loads a 250 KB fallback only for the browsers that lack it; on Android it runs on ML Kit and CameraX.
- Kept the test suite structurally confined to pure domain logic, so a green run means the arithmetic holds rather than that a route happened to work.
- Took the payment gateway all the way from sandbox to live production on an approved merchant account, alongside Google OAuth, R2 image delivery behind a CDN, and product analytics.
Feb 2026 – Jun 2026

5 mos
Full-Stack Web Developer Instructor

Tempa, led by Dicoding · Remote
- Taught full-stack web development across the program's five-month run.
- Tempa closed at a 92% graduation rate across its contributors.
Oct 2025 – Dec 2025

3 mos
React Backend & AI Instructor

Asah, led by Dicoding · Remote
- Taught JavaScript backend development to 70+ students across in-person learning sessions.
- Used interactive teaching strategies to lift engagement and comprehension.
Feb 2023 – Dec 2024

1 yr 11 mos · 6 roles
Mobile Development Instructor & Mentor

Bangkit Academy, led by Google, GoTo & Traveloka · Remote
1. Mobile Development Advisor Nov 2024 – Dec 2024
2. Mobile Development Instructor cohort 2 · 2024 Aug 2024 – Dec 2024
  - Taught Kotlin Android development to 50 students; the cohort reached a 91% graduation rate.
  - Held a 4.76 / 5.0 instructor rating.
3. Mobile Development Advisor May 2024 – Jul 2024
4. Mobile Development Instructor cohort 1 · 2024 Jan 2024 – May 2024
  - Taught Kotlin Android development to 50 students; the cohort reached a 93% graduation rate.
  - Held a 4.73 / 5.0 instructor rating.
5. Mobile Development Mentor batch 2 Aug 2023 – Jan 2024
  - Led and mentored a group of 25 students through the Android track to a 86% graduation rate.
  - Supported ILT sessions as timekeeper and prep, keeping students engaged throughout.
6. Mobile Development Mentor batch 1 Feb 2023 – Aug 2023
Aug 2022 – Dec 2022

5 mos
Backend Engineer Intern

Traveloka · Financial Services
- Shipped new features in the Financial Services domain in a production codebase.
- Wrote unit and automated tests for the team's work; built Know-Your-Business (KYB) flows for verifying financial partners.
KotlinSpring Framework
Aug 2021 – Jun 2022

11 mos
Laboratory Assistant

Universitas Multimedia Nusantara
- Ran lab sessions in probability & statistics, web dev, and mobile development.
- Taught HTML/CSS/JS, PHP, and Android (Java) to groups of 25–40 students.
- Graded and reviewed assignments across all three subject areas.
Mar 2020 – Dec 2021

1 yr 10 mos
Software Engineer

Arxist
- Built a full-stack English assessment platform for Politeknik Penerbangan Indonesia Curug.
- Developed the Laravel backend and integrated it with the web front-end.

04.1volunteering

Jul 2024 – Aug 2026 · 2 yrs 2 mos

Front of House

Google for Developers · Jakarta

Preparing the presentation material and checking the equipment before an event starts, then keeping the session running to schedule on the day, in constant coordination with the live streaming team.

2026: Cloud Next Extended Jakarta × KodingDeepDive Build with AI, Cloud Jakarta
2024: DevFest, Cloud Jakarta Google I/O Extended, Cloud Jakarta

Nov 2019 – Jan 2020

Google Code-in 2019 Mentor

OpenWISP · open source

OpenWISP is an open-source network management system for building low-cost networks. As a mentor I sat on the reviewing side of the contest.

Reviewed student task submissions
Authored new tasks to OpenWISP's standard
Ran quality assurance on student GitHub contributions

Oct 2018 – Dec 2018

Google Code-in 2018 Student

OpenWISP · open source

The year before mentoring, I was on the other side of it: 26 completed tasks against the OpenWISP codebase, and the run that ended in a Grand Prize.

Built a commit message style check
Contributed to OpenWISP quality assurance
Created an LXD deployment

earlier · community

2020–2021 IT Division, U-Store UMN Gen 4
2017–2018 Vice Leader, IT Community
2016–2017 LITBANG RPL, IT Community

05stack

Tools I actually reach for.

Highlighted items are the ones I'm fastest in; the rest I'm comfortable being dropped into. Tools are the easy part; the hard part is deciding what not to build.

languages · 09: PHPTypeScriptJavaScript KotlinSwift GoPython JavaObjective-C
backend & apis · 08: LaravelLumen FilamentNode.jsExpress HonoFlaskSpring
data · 07: PostgreSQLMySQLCloudflare D1 RedisCloudflare KV MongoDBFirebase
llm tooling · 03: ClaudeCodexMiniMax
platform & ops · 09: Cloudflare R2Google Cloud NginxComposer systemdDockerCloudflare Workers Cloudflare QueuesCloudflare Email
mobile · 05: SwiftUIKotlin Jetpack ComposeAndroidRevenueCat
frontend · 05: ReactVite Vue.jsNuxtJSNext.js
design · 01: Figma

06education

How I've learned.

Mar 2026 – Aug 2026

Apple Developer Institute for Entrepreneurship

Catalyst Program (Nada / Tunelab) · Jakarta · Hybrid

A six-month follow-on program for teams taking an Apple Developer Academy project toward a real business. I went through it with Nada.

Product and go-to-market development
Building on top of Apple platforms
Hybrid, cohort-based

Feb 2025 – Dec 2025

Apple Developer Academy

Bali · Cohort 2025 · iOS Developer Internship

A ten-month intensive focused on iOS development and the entrepreneurial side of shipping native apps end to end, built around Challenge Based Learning with cross-functional student teams.

Swift & SwiftUI
App design and prototyping
Core Apple frameworks: CoreMotion, Watch Connectivity, Multipeer
Agile project management

Aug 2019 – Jan 2024

Universitas Multimedia Nusantara

B.Sc. Information Systems · GPA 3.85 / 4.00

Information systems with a heavy dose of software engineering, algorithms, and data foundations.

Algorithms & data structures
Web design & development
Mobile application development
Artificial intelligence
Big data analytics

Feb 2022 – Jul 2022

Bangkit Academy

Mobile Development Cohort · Google, GoTo & Traveloka

Career-readiness program focused on in-demand mobile skills: Kotlin, fundamental and intermediate Android, UX design, SOLID principles, and career development. One of three thousand students in the cohort; graduated with Distinction (top 10%) on the Mobile Development path and served as a peer tutor for Android Fundamentals. I came back as a mentor in 2023 and an instructor across both 2024 cohorts.

07credentials

Certifications & recognition.

Google · Jul 2022

Feb 20191stTangerang Skill Competition, Web Design & DevelopmentDitsmk
Nov 20181stWeb Design LINEA 2018SMKN 5 Tangerang
Apr 20182ndBanten Skill Competition, Web Design & DevelopmentDitsmk
Feb 20181stTangerang Skill Competition, Web Design & DevelopmentDitsmk
Jan 2018·Google Code-in 2017 ParticipantGoogle
Dec 20171stWeb Design LINEA 2017SMKN 5 Tangerang
Mar 20172ndTangerang Skill Competition, Web Design & DevelopmentDitsmk
Oct 20163rdWeb Design LINEA 2016SMKN 5 Tangerang

08contact

Got a system that's outgrown its first design?
Let's talk.

Backend and platform work, API design reviews, the occasional teaching engagement. Happy to talk about any of it. I read everything that isn't a recruiter template.

rezajuliandri.my.id/contact

curl -s rezajuliandri.my.id/contact

{
  "email":    "[email protected]",
  "github":   "ppabcd",
  "linkedin": "rezajuliandri",
  "timezone": "Asia/Jakarta (UTC+7)",
  "replies":  true
}

[email protected] email → GitHub @ppabcd ↗ LinkedIn /in/rezajuliandri ↗ Kredibel current employer ↗

RezaJuliandri

The unglamorous half of the product.

How I usually build.

01Loose coupling

02Migrations

03Auth & errors

04Coverage

What I mean by clean.

Selected projects.

Nada by Tunelab

English Electronic Assessment

Clinic Web App

Stecy

Cultrip

Where I've worked.

Kredibelcurrent

Co-Founder · Tech Leadcurrent

Founder · Sole Engineercurrent

Full-Stack Web Developer Instructor

React Backend & AI Instructor

Mobile Development Instructor & Mentor

Backend Engineer Intern

Laboratory Assistant

Software Engineer