How Do I Know Whether My POS or Accounting Software Can Actually Connect to a Website?

Ask your current system provider three direct questions: does the system have an open API? Does it support webhooks for events like new orders or stock changes? And is there an additional cost for API access beyond the standard package fee? If the answer to the first two is yes, integration is technically feasible. If not, that does not necessarily end the conversation — there are alternative approaches.

What If My Current System Has No Open API at All? Is There Any Other Way?

Yes. The most common workaround is scheduled file export and automated import: the old system exports data as a file on a schedule, and middleware picks it up and loads it into the other system. It is not real-time, but it eliminates double-entry and still keeps records in sync. Whether that is acceptable depends on how time-sensitive your data needs to be.

If I Connect My Systems, Do I Have to Stop Using My Existing POS?

No. Integration creates a bridge that makes both systems communicate automatically. Your existing POS continues operating exactly as it does today. What changes is that data entered in the POS no longer needs to be manually re-entered in the website or back-office system — it flows across automatically.

How Is This Article Different from the One About Online Queue Booking Systems?

The booking system article is about the customer-facing experience — what happens when a customer interacts with your business. This article is about back-office data flow that happens entirely invisibly to customers: stock levels moving between systems, orders updating accounting records, sales figures consolidating across channels. Two different layers of the same business.

I Already Take Orders Through LINE Directly — Can Those Be Connected to Back-Office Systems?

Yes. Orders received via LINE can be recorded into your back-office system and linked to stock and accounting records. This is a separate workflow from the LINE OA broadcast quota — it concerns the order data itself, not the messaging quota. The specific integration depends on how you are currently recording those LINE orders.

I Have Multiple Points I Want to Connect at Once — Where Do I Start?

Start with whichever point wastes the most time through double-entry, or whichever one causes the most errors when records go out of sync. Fix that one first and stabilise it before moving to the next. Connecting everything at once multiplies complexity and makes it harder to pinpoint problems when they occur.

Connect Your POS or Shop System to Your Website — Stop Double-Entering Orders

Picture an employee standing in the middle between two people who speak completely different languages. On one side is the cashier at the front counter who knows every button on the POS terminal. On the other side is the website screen where an online customer is adding items to their cart right now. This employee isn't translating spoken words — they're translating numbers. Every time an order comes in through the website, they have to type it again into the POS to update the inventory to match what's actually on the shelf. And when someone buys in-store, they have to go back and update the website's numbers so the remaining stock doesn't mislead the next online customer. This translation job never stops, and the better the shop sells, the more translation work piles up.

I've met many shop owners who play this translator role themselves. Some hire an extra employee specifically for this job — without realizing that the entire salary is going toward work that creates nothing new. It's just moving the same numbers from one place to another, day after day.

Every time someone has to type the same data in two places, that's not diligence — it's a signal that the two systems aren't communicating.

This article is purely about back-office work — not the side customers see. If the pain point is customers double-booking appointments or tables, that's a different topic I've covered at 5 Reasons Your Shop Should Use an Online Booking System. Here we'll focus specifically on what happens behind the scenes — between the system you use to manage inventory or accounting and the website customers never see the back of.

Check Your Own Shop in Three Minutes First

Before looking at why two systems can't talk to each other, answer these questions for yourself. You don't need perfect answers — just enough to see where your shop stands.

When an order comes in through your website or chat, does someone have to manually type the same details again into your POS, accounting software, or stock spreadsheet?
Have you ever had a situation where the website said something was in stock, but when the customer arrived there was nothing left — or the reverse, shelves were full but the website showed it as out of stock?
If the person who does this data entry called in sick for a day, would the numbers in the two systems start drifting apart from that day forward?

If you answered yes to even one of these, your shop is wasting human time on work a computer could do instead. The question is how much. Do a quick calculation: take the number of orders that need to be re-entered per day, multiply by the average time each entry takes, then multiply by the number of days your shop is open per month. That gives you hours per month lost to pure data re-entry. A shop with 40 orders per day, spending 2 minutes re-entering each one, open 26 days per month, loses nearly 35 hours per month — roughly equivalent to a part-time employee's full month of work. And that figure doesn't count the time spent fixing entry errors.

Why Two Systems Can't Understand Each Other

Your POS, your accounting software, and your website were most likely built by different companies. Each was designed to store its own data in the way that best fits its primary job. The POS is great at processing payments quickly at the counter. The accounting software is great at generating accurate tax invoices. The website is great at displaying products attractively and selling around the clock. But none of them was designed out of the box to know about the others. Someone or something always has to act as a bridge — the real question is whether that bridge is a person or an automated system.

Three Main Integration Approaches

When I talk with shop owners, the most common misconception is that integrating systems requires an API — and only an API. In reality there are three main approaches, each suited to different situations.

The first is manual export and import: export an Excel or CSV file from one system and import it into the other on a set schedule — every morning or every end of day, for example. The advantage is that it costs almost nothing to start. The disadvantage is that someone still has to trigger it every cycle, and data won't be real-time. Between one cycle and the next, the numbers on both sides can drift.

The second is an API that lets other systems pull or push data: your backend system opens a channel allowing your website to automatically pull data or push data in — without any button-clicking. One verified example in the Thai market is FlowAccount, an accounting program that offers an Open API for connecting with existing systems such as ERP, CRM, or POS (FlowAccount OpenAPI documentation, Introduction section). Note that access isn't granted immediately — you must first submit a request via FlowAccount's API access request form. Another example is ZORT, an inventory and order management system that offers an API allowing external services to sync product data, purchase orders, and orders — including pulling data from marketplaces like Shopee and Lazada before forwarding it onward via Open API (ZORT API V4 documentation).

The third is a webhook, which works the opposite of a pull-based API: the source system "pushes a notification" to the destination the moment an event occurs, without waiting to be asked. One verified example is the PEAK accounting program, which has Webhooks that automatically send data the instant a document is created, modified, or cancelled — such as quotations and receipts. For invoices and expenses, PEAK adds two more webhook events: when payment is made and when payment is cancelled. (Webhook documentation, PEAK Developers) This approach delivers the closest thing to real-time data, but it requires a destination system that's always ready to receive — which often means an additional middleware layer that receives, transforms, and forwards the data so both sides can understand it.

None of these three approaches is universally best. A shop just starting to reduce double-entry work can begin with export/import and move to an API or webhook later once order volume makes the investment in full automation worthwhile. If you want a deeper understanding of how APIs work and the different types, read more at What Is an API? The Tool That Connects Your Business Systems Professionally.

Where Integrations Tend to Break Before Anyone Sees It

Having an integration doesn't mean you're done. In real-world work, there are small points that often slip through and become larger problems later.

The first is mismatched product codes. The same product might have different SKU codes in each system. If nobody maps those codes correctly from the start, the integration will sync the wrong product — and nobody will know until a wrong item gets sold. The second is timing. If the system syncs every ten minutes instead of instantly, within that ten-minute window two customers could simultaneously buy the last unit in stock. The third is non-standard transactions — returns, exchanges, or order-specific discounts. Basic integrations are mostly designed around "sold, deduct from stock." Edge cases like these almost always require a human check afterward, even with an automated integration in place.

Another commonly overlooked point is who maintains the integration long-term. POS systems and accounting programs update themselves regularly, and sometimes those updates change the data format they output without much notice. If nobody is checking periodically, an integration that was working fine can quietly stop functioning — and by the time anyone notices, a week may have already passed. This is why it's worth discussing with the team building your system, from the very beginning, who is responsible for monitoring the integration after the project is handed over.

To be precise: system integration doesn't eliminate the need for human oversight entirely. It shifts the work from re-entering every record to only reviewing the ones that are flagged as anomalies.

What If Your Current System Has No API to Connect?

I understand that many shops use software they purchased years ago, or Excel sheets they built themselves from day one. These systems do their job well in their own way. I'm not saying you have to tear everything out and replace it. If your current system has no open API, there are still options — whether that's scheduled automated export/import instead of real-time data pulls, or a middleware tool that receives files from your existing system and converts them into a format your website can read.

The first thing to do before deciding anything is to ask your current system provider directly. The right questions to ask are roughly: Does this system have an API or developer documentation for integration? Does it have a Webhook that notifies automatically when a new order arrives or inventory changes? Does enabling the API or Webhook cost extra beyond the standard plan? And if neither is available, does it support scheduled data export at set time intervals? The answers to these questions will immediately tell you which of the three approaches discussed earlier is the right starting point for your shop.

Why Waiting Makes Integration Harder

The problem of double data entry doesn't scale linearly with sales volume — it scales faster. A shop with ten products and a shop with two hundred products don't have twenty times the problem, because more products mean a higher chance of mismatched codes or someone forgetting to update a particular entry. The longer you let manual entry continue, the more the data in each system drifts in different directions. By the time you're ready to integrate properly, the first task before connecting anything is auditing which data is correct and which isn't — which takes far longer than it would have if you'd integrated when the data was still clean.

Start with the Single Most Painful Point

You don't have to integrate every system at once. The approach that has worked well in practice is to identify the single most painful point first. If the main problem is stock showing available online when it's actually gone, start by syncing just the inventory numbers in one direction. If the main problem is manually entering web orders into your accounting system, start just there. Then move to the next point once the first one is running stably. Starting small means you see results faster, can fix mistakes more easily, and don't need the full budget in place before you begin. If you'd like to see what a real back-office system looks like when built for an actual shop, view examples at tumwebsme.com/system. And if you want to understand what a full back-office system includes and what drives the cost, read more at What Does a Back-Office System for SMEs Include, and What Determines the Price?

Before even choosing an integration point, some shops aren't yet sure whether they've reached the stage where they need a proper back-office system at all. Read the signals that tell you your business has outgrown Excel and LINE chat at Signs Your Business Has Outgrown Excel and LINE.

Another common question is about orders that come in through LINE chat directly, bypassing the website entirely. Those can also be connected to a back-office system — but that's a separate topic from the LINE OA package pricing, which charges based on broadcast message volume. Details on that are at LINE OA Package Pricing 2026.

A 30-Day Plan Before You Start Integrating

Week 1 — Count the actual leaks: For one full week, track how many times data is re-entered each day and how many minutes each entry takes. Multiply out to hours per month.
Week 2 — Ask your current system providers: Contact your POS, accounting software, or inventory system and ask directly whether it has an API or Webhook — and if so, what the additional cost is.
Week 3 — Choose the single most painful point: From your week-one numbers, identify which point consumes the most time or causes the most errors. Make that your starting point.
Week 4 — Talk to a web development team: Bring the answers from week two to a team that can help build the integration. Discuss which approach fits your chosen starting point and what scope makes sense to begin with.

How to Measure Whether the Integration Is Actually Working

After integrating, the two numbers to track every week are: how many times you still had to correct data manually, and how many times you found the two systems showing different numbers for the same thing. If both decrease steadily each week, the integration is working. If they stay flat or increase, it may mean the connection point you chose isn't actually where the core problem lives — worth going back to examine where the real source of error is.

Closing Thoughts

Whatever systems your shop is currently running — POS, accounting software, or even an Excel sheet — they each do their job well in their own way. The point of this article is to encourage you to build a small bridge between your existing systems and your website, so the person who has been spending their whole day translating numbers can go back to doing work that actually creates value for your shop. You don't have to start at the biggest point. Start with the one thing that hurts you every single day — that's enough.

If your shop is currently dealing with double data entry between systems and your website, feel free to message us and tell us what systems you're using. We'll help identify which point makes the most sense to connect first.