Custom Inventory & Warehouse Management System (WMS) Development in Thailand

Good inventory software means the number on screen matches the shelf

Any business selling physical goods asks the same questions every day: how many do we have, where are they, do we need to reorder? Simple questions, but when the answers come from three versions of a spreadsheet or from one warehouse person’s memory, the numbers drift until you sell stock you don’t have or find expired goods at the back of the store.

Southern Whale builds custom inventory and warehouse management systems around how your warehouse actually works: receiving, storage, issuing, branch transfers and syncing stock with your online channels. Staff scan barcodes with their phones, and you own the code and data.

Honestly: even the best system is wrong if staff don’t scan when goods move. Half our work is designing steps simple enough that your team does them every time.

---

What is a warehouse management system (WMS)?

A WMS manages every movement inside the warehouse: receiving, put-away to a location, picking in the right order, packing and shipping. What people call inventory or stock management software focuses on quantities on hand and stock movements per item.

For most SMEs the line doesn’t matter much. Start with accurate stock, then add WMS capabilities such as bin locations and pick lists once finding items becomes the bottleneck.

---

Who it’s for

• Wholesalers and distributors with hundreds or thousands of SKUs and multiple units (piece, pack, carton)
• Multi-branch retailers that transfer goods between branches
• Brands selling on several channels: website, Shopee, Lazada, LINE and a physical store, all from one stock pool
• Businesses with lots and expiry dates: food, beverages, cosmetics, supplements, clinic medicines and supplies
• Small and mid-sized factories tracking raw materials, work in progress and finished goods
• Resorts and hotels in Southern Thailand with several storerooms (kitchen, bar, housekeeping, maintenance) that need to know what each department draws

If you have a few dozen products, one channel and a spreadsheet that still works, you don’t need a custom system yet. We’ll say so.

---

Signs you need a proper system

• Stock counts never match and nobody knows where the difference went
• You oversell online and have to cancel orders, hurting your shop rating
• Goods expire while older lots sit unnoticed
• Checking stock means calling the warehouse
• Best-sellers run out while slow movers fill the shelves
• You can’t work out real cost per unit because you bought at different prices
• The spreadsheet is slow, or several spreadsheets disagree

---

Modules we build

Picking vs costing: which physical unit leaves the shelf first (FEFO for perishables) is separate from how cost is calculated for accounting (FIFO or average). The system keeps them independent.

---

Custom vs off-the-shelf

A single standard warehouse with no lots usually fits off-the-shelf software better. Custom wins when your process is specific or per-user fees climb with headcount and branches. A middle path is an open-source base such as Odoo with targeted customisation; we’ll tell you which suits your scope. See also custom software development.

---

Our process

1. Discovery — walk the warehouse, talk to the people doing the work, document scope in writing
2. Prototype — clickable key screens (receiving, scan-to-issue, stock count) tested by your team
3. Phased rollout — core stock first in one warehouse, then more branches and channel integrations
4. Training — role-based sessions and an illustrated manual in Thai or English
5. Handover — source code, documentation, database and admin access, so you can change teams if you ever need to

---

Integrations

• Online channels: your e-commerce website, Shopee and Lazada via their APIs
• Store front: a POS system that deducts from central stock
• ERP and accounting: a full ERP system, or export to Express, FlowAccount or PEAK
• LINE alerts for low stock, near-expiry items and pending transfers
• Excel import and export on every main screen

---

Data migration

We collect your product data from Excel or the old program, clean duplicates and unit mismatches, import to a test system for your review, then do a physical opening count before go-live. Historical movements can be migrated if the old system exports them completely; if not, we tell you during scoping.

---

Security and PDPA

Role-based access (cost prices visible only to authorised users), a full audit log of every receipt, issue, transfer and adjustment, approval for stock adjustments, automated backups with restore testing, minimal personal data handled in line with Thailand’s PDPA, HTTPS throughout and API keys stored outside the code.

---

Get started

Southern Whale has delivered 50+ websites, and our founder brings 10+ years of web and systems experience. We start every project by understanding how you actually work.

Priced on real scope — message us on LINE @969dkzqz for a free consultation first, or email [email protected]. Tell us how many warehouses you have, roughly how many products, and which channels you sell on, and we’ll tell you honestly whether off-the-shelf or custom fits better.

Frequently asked questions

What is a WMS and how is it different from basic inventory software?

A WMS (Warehouse Management System) manages work inside the warehouse: where each item is stored, who picks it and in what order. Basic inventory software mainly answers how much of each item you have. Most SMEs start with accurate stock tracking and add WMS features such as bin locations and pick lists as the warehouse grows.

Can staff scan barcodes with a phone instead of a dedicated scanner?

Yes. The system runs as a web app that works in a phone browser and uses the camera to scan barcodes and QR codes. For very high scan volumes a rugged warehouse scanner is faster and more durable; the system supports both.

Our products don't have barcodes yet. Is that a problem?

No. The system can generate item codes and print barcode or QR labels for products, lots and storage locations on a standard thermal label printer.

Can stock really sync with Shopee, Lazada and our website?

Yes, through each platform's API. A sale on one channel reduces central stock and pushes the new quantity to the others. Sync follows each platform's rules and timing, so for fast sellers we recommend holding a small buffer to reduce the chance of overselling between updates.

Can you handle lots and expiry dates (FEFO)?

Yes. Lot numbers and expiry dates are captured at receiving, and when issuing the system suggests the earliest-expiring lot first. Near-expiry reports warn you a set number of days in advance.

Will it work with our accounting software?

Yes. Purchase, sales and cost data can be exported to programs such as Express, FlowAccount or PEAK in whatever form they support, via API or import file, so your accountant keeps working in the tool they already use.

Can you migrate our stock data from Excel or an old program?

Yes. We prepare Excel import templates, clean duplicate codes and unit mismatches, and recommend a physical opening count before go-live, because spreadsheet balances are rarely accurate.

Why not just use an off-the-shelf inventory app?

If your workflow matches what the app was built for, a subscription is usually cheaper and faster to start, and we'll tell you so. Custom makes sense when you have multi-warehouse transfers, lots and expiry, or integrations that standard apps can't handle.

How much does a custom inventory system cost?

Priced on real scope — message us on LINE for a free consultation first. We learn about your warehouses, products and workflow, then send a written scope.