Payment Gateway API
Payment Gateway API, Payment Channel API, and merchant Payment API integrations describe the same practical boundary: your systems call SoPay over HTTPS to collect funds (Merchant Collection API / payin), send funds (Merchant Payout API / payout), query orders, and consume signed webhooks. SoPay Docs is the reference for that integration layer across multiple countries.
This guide orients product and engineering leaders. Per-country field lists remain in each market’s overview—for example India Payment API documentation or Thailand Payment API documentation.
What a payment gateway API does for merchants
From your application’s perspective, a Payment Gateway API provides:
| Function | Merchant benefit |
|---|---|
| Payin | Accept local currency from end users |
| Payout | Disburse to suppliers, players, or sellers |
| Queries | Reconcile when callbacks lag |
| Webhooks | Near-real-time terminal status |
| Signatures | Cryptographic proof of origin |
SoPay sits between your backend and localized payment channels. You avoid direct contracts with every bank, wallet, or clearing network in each country you serve.
Third-party vs fourth-party models (industry language)
Teams sometimes distinguish:
- Third-party payment API — a licensed or regulated aggregator connects merchants to banking rails; merchants integrate that aggregator’s Payment Gateway API
- Fourth-party payment API — an additional technical or commercial layer unifies multiple aggregators; merchants still see one Payment Channel API surface
SoPay documentation describes merchant-facing APIs regardless of where your business sits in that stack. Legal licensing and channel ownership are defined in your commercial agreement—not inferred from this developer site.
Core modules in SoPay Docs
| Module | Role | Entry points |
|---|---|---|
| Payin | Merchant Collection API | Country /payin pages, e.g. Thailand Payin |
| Payout | Merchant Payout API | Payout API guide, India overview |
| Callback | Async notifications | Merchant Callback API |
| Signature | RSA2 sign/verify | Merchant Signature Verification |
| Wallet | Balance and ledger | Country overviews where enabled |
Cross Border Payment API structure
SoPay documents Cross Border Payment API programs as country + currency modules, not a single global schema:
| Market | Solution guide | Technical overview |
|---|---|---|
| India | India Payment API | India documentation |
| Thailand | Thailand Payment API | Thailand documentation |
| Pakistan | Pakistan Payment API | Pakistan documentation |
| China | — | China documentation |
Additional countries appear on Supported Countries.
Choosing a reading path
- Payout-only product → Merchant Payout API + target country payout doc
- Checkout-only product → country payin documentation
- Security architecture → Signature + Callback first
- Single-market launch → country solution page + overview
Start onboarding with Quick Start.
Frequently Asked Questions
Does SoPay offer one global Payment API endpoint?
No. Endpoints and payloads are scoped by merchant country configuration (countryCode, currency). Multi-country merchants implement each module separately while reusing signing and webhook handlers where possible.
Open API vs header-signed REST—which applies?
Documentation includes historical variants. Use the credential pack for your merchant and the target country overview—do not mix authentication styles.
What must webhook endpoints return?
After verification and successful processing: HTTP 200 with plain text OK. See Merchant Callback API.
Where are error codes listed?
Country appendix pages (for example India error tables) or operations-provided supplements.
Is this page a substitute for API reference?
No. It explains Payment Gateway API concepts and links to authoritative reference pages.