Automation & Payment Systems Engineer

I automate the work your business shouldn't do manually.

I engineer business automation, AI workflows, type-safe APIs, and payment systems that eliminate repetitive bottlenecks — so your team can focus on what actually grows the business.

Let's Automate See My Work

lejaprianza@gmail.com Indonesia

The Problem

Your team is doing work that software should handle.

If any of this sounds like your normal workday, that time is 100% recoverable.

Sending invoices and payment reminders by hand

Copying data from one system to another, manually

Checking and reconciling payments one by one

Connecting tools that don't talk to each other

Repeating the same admin work every single day

Processing customer data by hand

Sending the same WhatsApp messages over and over

Building weekly reports manually

What I Do

Four ways I remove repetitive bottlenecks from your business.

Business Automation

Problem

Your team loses hours every week moving data between tools and repeating the same steps.

Solution

I connect your tools — WhatsApp, email, Google Sheets, databases, and more — into workflows that run themselves.

Repetitive tasks done in seconds, without human error, 24/7.

n8nAPIsWhatsAppEmailGoogle SheetsDatabasesAI

Payment Integration

Problem

Payments are manual: you check notifications, verify each one, and reconcile by hand.

Solution

I build and integrate payment gateways, webhooks, pay-in, payout, and settlement systems — end to end.

Every payment tracked, verified, and reconciled automatically.

Payment GatewaysWebhooksPay-InPayoutSettlementReconciliation

High-Performance Backend & APIs

Problem

Slow APIs, fractured databases, and systems that fail under real transaction loads.

Solution

I design high-throughput backend services, type-safe REST APIs, relational schemas, and robust auth with Bun & ElysiaJS.

Blazing fast response times and 100% type safety from database to UI.

BunElysiaJSTypeScriptDrizzle ORMPostgreSQLSupabaseEden Treaty

AI Workflow Automation

Problem

Simple decisions and repetitive responses eat up your team's productive time.

Solution

I plug AI into your workflows — customer support, document classification, content, reports — so routine work handles itself.

Faster responses, happier customers, and zero hours lost to repetitive tasks.

Customer SupportData ClassificationContentReportsAI APIs

Selected Production Work

Real systems, engineered for real business cash flow.

Every case study represents live production software processing real transactions and mission-critical automated workflows.

Subscription & Billing System

OnlySubs

A chatbot-based automated subscription lifecycle and billing management engine for merchants.

The Problem

Merchants were managing subscription customers by hand — tracking who owed what, sending reminders, and collecting payments manually.

The Solution

I built an automated subscription chatbot that handles customer onboarding, billing, and payment collection seamlessly. Merchants run their entire subscription business right from chat.

The Outcome

The entire subscription lifecycle — onboarding, invoicing, payment verification, and renewal reminders — runs automatically 24/7.

Architecture Highlights

Supabase & PostgreSQL schema tailored for recurring subscriptions
n8n workflow engine orchestrating cross-system events and triggers
Telegram & WhatsApp conversational UI for frictionless merchant operations
Xenith payment gateway integration for automated payment collections
Svelte / Next.js management portal with real-time analytics
Automated CI/CD pipelines with GitHub Actions for zero-downtime shipping

Tech Stack Applied

SupabasePostgreSQLn8nTelegramWhatsAppPayment GatewaySvelteGitHub Actions

Fintech Infrastructure

Payment Middleware Engine

A high-throughput pay-in, payout, and settlement engine that routes transactions across multiple payment gateways.

The Problem

Handling payments across multiple regional gateways meant manually tracking every transaction from payment through settlement, fee deduction, and bank disbursement.

The Solution

I built a resilient payment middleware that dynamically routes merchant transactions, verifies webhooks with cryptographic signatures, tracks status to settlement, and automates payouts to merchant bank accounts.

The Outcome

Transactions flow securely from end-user to merchant bank account with automated fee deduction, instant reconciliation, and zero manual intervention.

Architecture Highlights

Dynamic pay-in routing across multiple gateways (Finpay, Xenith, and more)
Secure webhook engine with cryptographic signature verification
Automated transaction lifecycle tracking from pending through settlement
Settlement aggregation clearing collected funds with automated merchant fee deduction
Automated payout and disbursement engine direct to merchant bank accounts

Tech Stack Applied

Payment GatewaysWebhooksHMAC SignaturesPay-InPayoutSettlementHigh-Throughput Backend

How It Works

From manual chaos to automated precision in three steps.

01 STEP 01

Tell me what you're doing manually

Send me a message describing the task. I'll ask the right questions to understand your exact operational process.

02 STEP 02

I design and build the automation

I map the workflow, build the system, and test it against your real-world scenarios before you go live.

03 STEP 03

Your workflow runs itself

The work gets done automatically, payments reconcile in real-time, and you get your time back.

Why Work With Me

An engineer who ships production value, not tech hype.

Real fintech experience

I build production payment infrastructure inside a BI-regulated cross-border payments company.

Ultra-fast modern stack

Specialized in Bun, ElysiaJS, Svelte 5, and Drizzle for maximum throughput, low memory footprint, and instant loads.

Production systems, not demos

I design backend architecture, databases, and APIs that process real money and mission-critical data every day.

Full stack, problem to delivery

I take a problem from architectural design through backend APIs, reactive frontend, and CI/CD deployment.

Business outcomes over tech hype

I start with your business bottlenecks, then apply the right architecture to recover time and grow revenue.

One engineer, end-to-end

Automation, backend, APIs, frontend, and payments — built cleanly without communication overhead or handoff chains.

Dedicated Technology Stack

Engineered for speed, type safety & zero-downtime scale.

A focused, modern architecture selected specifically to maximize system throughput, eliminate manual errors, and provide seamless user experiences.

100% Type-Safe & Cloud-Compiled

Core Engine

High-Throughput Backend & APIs

Engineered for sub-millisecond execution, type-safe RPC contracts, and native async I/O under real transaction loads.

Core Technologies

Bun Runtime

ElysiaJS

TypeScript (Strict)

Eden Treaty (E2E RPC)

REST APIs

OpenAPI / Swagger

Persistence

Database & Data Architecture

Zero-overhead relational queries, automated versioned migrations, and high-availability connection pooling.

Core Technologies

PostgreSQL

Drizzle ORM

Supabase

Versioned SQL Migrations

Atomic Transactions

ACID Compliance

Client UI

Reactive Frontend Systems

Fine-grained reactive interfaces with zero virtual DOM overhead, accessible design primitives, and instant loads.

Core Technologies

Svelte 5 (Runes)

SvelteKit (SSR)

Tailwind CSS v4

shadcn / bits-ui

Lucide Icons

Responsive Motion

Integrations

Automation & Payment Infrastructure

Production-grade payment gateways, autonomous workflow loops, and multi-channel messaging integrations.

Core Technologies

n8n Workflow Engine

Payment Gateways (Pay-In/Payout)

Real-Time Webhooks

Telegram Bot API

WhatsApp Business API

AI Agent Workflows

Deployment

DevOps & Cloud Infrastructure

Automated cloud compilation on 16GB RAM runners, zero-git VPS deployments, auto-healing resource guards, and SSL.

Core Technologies

Docker & Compose

Caddy (Auto-HTTPS)

GitHub Actions CI/CD

GitHub Container Registry (GHCR)

Linux Ubuntu VPS

Anti-OOM / Anti-Disk Guards

Resilience

Security & Reliability Engineering

Hardened security primitives, cryptographic signature verification, idempotent mutations, and graceful error recovery.

Core Technologies

HMAC Signatures

Idempotent Mutations

TypeBox Runtime Guards

Rate Limiting & CORS

Audit Trail Logging

Fail-Safe Rollbacks

No Legacy Code, No Slop

Every component and backend route is rigorously typed, tested, and optimized for sub-100ms cold starts.

Discuss Architecture

Let's Work Together

Ready to eliminate manual bottlenecks?

Tell me about your business process, transaction challenges, or automation bottlenecks. I'll review your workflow and outline the optimal technical roadmap.

Direct Email

lejaprianza@gmail.com

Send an Inquiry

Fast response within 24 hours.