Full-Stack Developer & AI Automation Engineer · Ho Chi Minh City

Vo Duy
Bao Khanh

I build automation that keeps working while everyone sleeps: 29 production workflows, multi-agent chatbots, and the plumbing that makes them safe to trust.

See the systems GitHub

Sample run log · illustrative

✓ zalo.webhook 3 msgs merged → 1 LLM call
✓ etl.sheets→pg 8 catalogs swapped, 0 s downtime
✓ order.alert idempotent ON CONFLICT DO NOTHING

4+ years shipping production software

29 active n8n workflows, 500+ nodes

500+ customer messages a day handled by AI agents

~60% LLM token cost cut by debouncing

Systems that run on their own

Five pieces of the Nava Store & NavaTek automation stack. Pick one to see the problem, the mechanism, and what changed.

Customers type in bursts. The bot answers once.

A three-stage multi-agent assistant on Zalo OA that quotes real prices from the database, routes VAT and warranty, and steps aside the moment a human joins.

Zalo webhook
Dedupe
Lock + JSONB buffer
Grace wait
Merge text
Classify intent
Agent A · B · C
Reply or hand off

Problem: Webhooks fire per message. Four short texts meant four parallel runs, four LLM bills, and answers that talked over each other.
Mechanism: A PostgreSQL row is the distributed lock. Messages that arrive while it is held go into a JSONB buffer, merge after a quiet period, and reach the model once. Agent A finds the need, B quotes from live DB tools, C closes the order. A [STAGE:x] marker moves the conversation between them.
Outcome: About 60% fewer tokens, no overlapping replies, 500+ messages a day. Staff replies are detected and mute the bot instantly.

n8n
PostgreSQL
Gemini Pro/Flash
Gemini Vision
LangChain
Zalo OA
Lark

One order, one alert. Even when the webhook fires three times.

Orders from Shopee, TikTok Shop, Lazada and the web storefront land in one event-driven router that tells the warehouse what to pack and when.

Sapo webhook
Express order?
INSERT … ON CONFLICT
Working hours?
Lark card now
Or night queue
08:00 digest

Problem: Providers retry webhooks, delete them without warning, and an order can turn into an express order after the first alert went out.
Mechanism: ON CONFLICT DO NOTHING RETURNING makes alerts idempotent at the database. The Lark card id is stored, so a normal order that becomes express is edited in place into a red alert instead of spawning a second message. Every 6 hours the workflow audits Sapo webhooks and re-registers missing ones; every 10 minutes it reconciles web orders against the ERP.
Outcome: Zero duplicate notifications, orders that fail to reach the ERP are flagged within minutes, and night orders arrive as one 08:00 digest instead of waking anyone.

n8n
PostgreSQL
Sapo GO / Web
Shopee
TikTok Shop
Lark cards

The bot never sees an empty table.

Sales edit prices in Google Sheets all day. The chatbot reads them from PostgreSQL. Between the two sits a Blue/Green swap.

Read 8 sheets
Normalise + slug
Load stage tables
Assert rows > 0
Atomic swap
Live, 0 s gap

Problem: DELETE then INSERT on the live table leaves a window where a failed sheet read means an empty catalogue and a chatbot that lies.
Mechanism: Data loads into products_stage and lap_may_stage. An assertion raises an exception if a stage table is empty, which rolls the transaction back. Only then do the tables swap atomically.
Outcome: 8 catalogs sync every 2.5 hours with integrity checks, and the chatbot's data is never partial.

PostgreSQL
PL/pgSQL
Google Sheets
n8n

An internal assistant that cannot leak what you may not read.

An Obsidian-style knowledge base with a RAG assistant. Answers cite their sources, and permissions are enforced before retrieval, not after.

Expand query (6 turns)
Vector 1024-d
Full-text unaccent
RRF merge
bge-reranker top 6
Cited answer

Problem: Hybrid search finds the right document, including ones the asker must never see.
Mechanism: Folder RBAC and ACL on PostgreSQL ltree with inheritance, DENY-first, personal rules over department rules. Restricted documents vanish from the tree and from retrieval. Clicking a citation opens the source with the cited passage highlighted.
Outcome: One assistant for the whole company where access control is a property of the data, not of the prompt.

Python
PostgreSQL
ltree
Next.js
bge-reranker-v2-m3
RRF

Tools people use every day

Internal full-stack apps that replaced spreadsheets, manual clicks and guesswork.

Banner Studio
1024×1024 Shopee covers from a product photo. RMBG-1.4 background removal and LaMa inpainting in worker threads, warranty-badge template matching, Excel batch to ZIP.
NestJS · Next.js 15 · ONNX
Metadata Tool
Batch image metadata scrubbing that never uploads a byte: 8-thread queue, EXIF/IPTC/XMP editing, export straight to a folder.
TypeScript · Web Worker · ExifTool WASM
Warehouse scan console
Barcode, DataMatrix and OCR label scanning, packing video capture, 50×20 mm QR labels, and stocktaking with atomic serial rollback.
Express 5 · Flask · PostgreSQL
Price watch & pricing matrix
Competitor price crawler with change alerts, plus a multi-channel pricing matrix that blocks sell prices under the floor.
Playwright · Cheerio · Streamlit
NameSEO
Rewrites marketplace product titles to a 110–120 character formula with Gemini, validates the result, and asks for a fix up to twice before flagging it for a human.
Next.js · Gemini
Theme Sync extension
Pushes local theme edits to the Sapo Web Admin API every 2 s, with conflict detection and a hard refusal to publish an empty file.
Chrome Extension · Sapo Liquid
Quote PDF daemon
Polls Lark every 20 s, renders the quotation and handover PDFs, and attaches them back to the record.
Python · WeasyPrint · Lark API
AI product search & warranty lookup
Gemini-powered storefront search and a rate-limited, data-masking warranty proxy for navatek.vn and navastore.vn.
PHP · Sapo V2 · Gemini

Public on GitHub

The production systems above are private. These are open.

All repositories →

Where I have done it

Jan 2026 – now
Nava Store & NavaTek
Full-Stack & AI Automation Engineer

Architected the whole automation ecosystem: 29 active n8n workflows (500+ nodes) on self-hosted Docker, joining Sapo ERP, Zalo OA, Lark, Shopee, TikTok Shop and PostgreSQL. Manage OAuth2 token lifecycles with rotating refresh tokens and IP-whitelisted calls. Ship internal apps across Node.js, Next.js, NestJS and Flask.
Aug – Dec 2025
Ape Tech Solutions
Full-Stack Developer

Mobile and backend features for pickleball booking and F&B warehouse systems in React Native, Flutter, NestJS and PostgreSQL. Cut query latency with schema work and Redis caching; refactored legacy Flutter state management.
Jan 2024 – Jan 2025
BIT Group
Backend Developer

Go and MySQL REST APIs integrated with Lark for time-tracking and HR automation. Rebuilt legacy endpoints with JWT and role-based access control.
Jan 2022 – now
Freelance
Mobile & Web Developer

Custom apps for small businesses in Go, Kotlin, ReactJS, PHP and MySQL, from architecture to Docker deployment, with ZaloPay, Firebase and Haravan integrations.

Toolbox

Languages: TypeScript · JavaScript · Python · Go · SQL (PL/pgSQL) · PHP · Kotlin · HTML/CSS
Frameworks & AI: Node.js · NestJS · Next.js · Express · Flask · Streamlit · React · React Native · Flutter · LangChain · Gemini API · RAG · ONNX
Automation & APIs: n8n · Playwright · Zalo OA · Lark Suite · Sapo Omni/GO/Web · Shopee & TikTok Shop APIs · Apps Script
Data & DevOps: PostgreSQL (JSONB, ltree, pg_trgm) · MySQL · Redis · SQLite · Docker · Ofelia · OliveTin · Nginx / Caddy · Cloudflare Tunnel

Have something that should run itself?

khanhvo908@gmail.com

GitHub LinkedIn Ho Chi Minh City

Vo DuyBao Khanh

Customers type in bursts. The bot answers once.

One order, one alert. Even when the webhook fires three times.

The bot never sees an empty table.

A cron server that wakes itself up and catches up.

An internal assistant that cannot leak what you may not read.

Banner Studio

Metadata Tool

Warehouse scan console

Price watch & pricing matrix

NameSEO

Theme Sync extension

Quote PDF daemon

AI product search & warranty lookup

Nava Store & NavaTek

Ape Tech Solutions

BIT Group

Freelance

Have something that should run itself?

Vo Duy
Bao Khanh