Service
Payment Gateway & e-Payment Integration
Take payments online and have them land in your books without anyone retyping them
Connect online payments to the systems that run your business: PromptPay, cards, and bank transfers wired into your ERP, e-Tax Invoice, and daily reconciliation, with PCI scope kept small.
Who we connect payments for
Businesses where taking money is easy but matching it to an invoice, order, or account still takes a person.
Retail & E-Commerce
Checkout across web, app, and marketplace orders that needs one settlement view instead of three gateway dashboards.
Utilities & Property
Online bill payment for recurring invoices like water, electricity, and condo fees, matched back to the customer account automatically.
Education
Tuition and fee collection by QR or card, with receipts issued against the right student record and term.
Healthcare
Deposits, package payments, and outstanding balances paid online and posted to the hospital information system.
B2B Distribution & Manufacturing
Invoice-based payment, partial payments, and credit terms reconciled against accounts receivable in the ERP.
Public Sector & Associations
Fee and fine collection with e-Receipts and an audit trail that holds up to review.
How we deliver a payment integration
Four phases. You go live on one channel first, then add the rest once the money is reconciling cleanly.
- 01
Assess
Map every way money comes in today: channels, payment methods, who reconciles what, and where it lands in the ERP. Then pick a gateway on fees, settlement terms, and the methods your customers use.
- 02
Integrate
Build the payment flow, signed webhooks, and idempotent status handling. Cards go through the gateway’s hosted fields or tokenisation, so card data never touches your servers.
- 03
Connect
Post paid, refunded, and settled events to the ERP, issue e-Tax Invoices and e-Receipts, and generate the daily reconciliation report.
- 04
Operate
Go live on one channel, watch failed-payment and mismatch rates, then roll out the remaining channels and hand over runbooks.
What we integrate with
Payment methods, gateways, and back-office systems we connect. We recommend the gateway that fits your fees, settlement terms, and customers.
Payment Methods
- PromptPay / Thai QR
- Credit & debit cards
- Mobile banking
- Bank transfer
- Installments
- e-Wallets
Gateways
- 2C2P
- Opn Payments
- GB Prime Pay
- Bank payment APIs
- Stripe
Back Office
- SAP
- Microsoft Dynamics
- Oracle NetSuite
- Odoo
- Custom ERP
Tax & Compliance
- e-Tax Invoice
- e-Receipt
- PCI DSS
- 3-D Secure
- PDPA
Taking a payment online is the easy part. Every gateway ships a checkout page and a sandbox. The work that eats a finance team’s week comes after the customer pays: matching the transfer to the right invoice, issuing the e-Tax Invoice, posting the receipt to the ERP, and explaining why yesterday’s settlement is 3 baht short. We build payment integrations that start from where the money has to end up, not from the pay button.
Why is a payment gateway an integration problem?
Because the gateway only knows about the transaction. Your ERP knows about the customer, the invoice, and the account. Your tax system knows which document has to be issued. Your bank knows what actually settled, net of fees, one or two days later. When those systems don’t talk to each other, someone reconciles them by hand, usually in a spreadsheet, usually at month end. That’s the part we automate.
What we build and connect
- Online bill payment: recurring invoices paid by PromptPay QR, card, or mobile banking and matched back to the customer account automatically
- e-Tax Invoice and e-Receipt: documents issued the moment a payment is confirmed, in the Revenue Department format
- e-Invoice payment: pay links sent with an invoice, including partial payments and payments against credit terms
- ERP integration: paid, refunded, and settled events posted to accounts receivable in SAP, Dynamics, NetSuite, Odoo, or a custom ERP
- Payment reporting and reconciliation: a daily report that matches gateway settlements against orders and bank statements and flags what doesn’t match
- Payment APIs: one internal API for your website, mobile app, and back-office systems, so a new channel doesn’t need a new gateway integration
Keeping card data out of your systems
Card numbers are captured inside the gateway’s hosted fields or SDK and come back to you as a token. Your servers never see a full card number, which keeps your PCI DSS scope to the smallest self-assessment questionnaire the gateway supports. Webhooks are verified by signature and handled idempotently, so a retried notification never marks an order paid twice. Payer data is mapped for PDPA like any other personal data you hold.
If finance still has to retype payments into the ERP, the payment integration isn’t finished. The checkout just looks finished.
New system or existing one
We work both ways. For a new website or app we design the payment flow in from the start. For a system that already exists, whether it’s a legacy ERP, a booking engine, or an internal billing tool, we add the gateway alongside it and connect the back office without a rewrite. Either way we recommend a gateway on fees, settlement terms, and the payment methods your customers actually use.
If you’re adding a payment channel or tired of reconciling by hand, tell us how money comes in today. We’ll come back with a recommended gateway, the integration scope, and an estimate.
What changes after go-live
What we check before we call the integration done.
payments, refunds, and settlements flow into the ERP without manual entry
a settlement-to-order reconciliation report every morning, with mismatches flagged
on your servers. Card capture stays inside the gateway’s PCI scope
for web, app, and bill payment, so a new channel doesn’t need a new integration
FAQ
Frequently Asked Questions
Which payment gateways does HarmonyX integrate with?
We integrate with the gateways Thai businesses commonly use, including 2C2P, Opn Payments, GB Prime Pay, bank payment APIs, and Stripe for international cards. We don’t push one gateway. We recommend the one that fits your fees, settlement terms, and the payment methods your customers actually use, such as PromptPay QR, cards, mobile banking, and bank transfer.
Can you add a payment gateway to a system we already have?
Yes. Most of our payment work connects a gateway to an existing website, app, booking engine, or ERP without rewriting it. We add one internal payment API alongside the existing system, then post paid, refunded, and settled events into accounting and issue e-Tax Invoices and e-Receipts automatically.
How do you handle PCI DSS and reconciliation?
Card numbers are captured in the gateway’s hosted fields or SDK and returned as tokens, so your servers never hold card data and your PCI DSS scope stays minimal. Webhooks are signature-verified and idempotent, and a daily reconciliation report matches gateway settlements against orders and bank statements and flags anything that doesn’t match.
Building a new system, or adding payments to one you already run?
Tell us how money comes in today and where it needs to end up. We’ll come back with a recommended gateway, the integration scope, and an estimate.