WHMCS

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Who this is for

• You run a WHMCS billing panel (8.0 or newer) for hosting, domains, or any recurring service
• You want to accept eSewa and Khalti from Nepali customers in one module - no separate integrations to reconcile
• You already have (or can create) a PayBridgeNP account with a sk_live_… or sk_test_… API key
• Your invoice currency is NPR

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What you get

• eSewa + Khalti in one module. No per-method configuration, no duplicate webhook endpoints. Add any future PayBridgeNP provider without changing the module.
• Hosted checkout. Customers pay on a mobile-friendly page served by PayBridgeNP. No iframe embedding, no card input inside WHMCS - compliance surface stays small.
• Refunds from WHMCS admin. Click Refund on any transaction, including partial refunds. The module calls the PayBridgeNP refund API and records the result in the WHMCS Gateway Log. Note: eSewa refunds are accepted into a requires_action state and finalized by PayBridgeNP out of band, so an eSewa refund is not instant - confirm completion in the PayBridgeNP dashboard.
• HMAC-signed webhooks. Every payment.succeeded / payment.failed event is verified against an HMAC-SHA256 signature with a 5-minute replay window. Forged events are rejected with a 400 response.
• Idempotent payment application. Uses WHMCS’s checkCbTransID helper so replayed webhooks never double-post to tblaccounts.
• Gateway Log integration. Every API call, webhook delivery, and refund attempt is recorded in Utilities → Logs → Gateway Log with request/response context. API keys and signatures are automatically scrubbed before they land in the log - safe to share with support.
• Public Callback URL override. Optional field for installs behind a load balancer where the WHMCS System URL isn’t internet-reachable, or for local dev with a tunnel (cloudflared / ngrok).
• GPL-2.0-or-later licensed. Same license family as WHMCS itself.

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How it plugs in

┌────────────────┐  1. pays invoice (picks PayBridgeNP)    ┌───────────────┐
│   Customer     │ ───────────────────────────────────────▶│     WHMCS     │
└────────────────┘                                         └──────┬────────┘
                                                                  │ 2. paybridgenp_link()
                                                                  │    creates checkout session
                                                                  ▼
                                                         ┌──────────────────┐
                                                         │  PayBridgeNP     │
                                                         │  hosted checkout │
                                                         └────────┬─────────┘
                                                                  │ 3. customer pays (eSewa / Khalti)
                                                                  ▼
┌────────────────┐   5. return URL → invoice view         ┌──────────────────┐
│   Customer     │ ◀───────────────────────────────────── │  callback.php    │
└────────────────┘      (no state mutation here)          └──────┬───────────┘
                                                                  │
                                                                  │ 4. signed webhook (authoritative)
                                                                  ▼
                                                         ┌──────────────────┐
                                                         │  callback.php    │
                                                         │  → invoice Paid  │
                                                         └──────────────────┘

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WHMCS Marketplace

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What’s next

• Install the WHMCS module - download, extract, activate, configure (about 10 minutes)
• How it works - payment flow, invoice state transitions, webhook handling, security model
• Troubleshooting - common issues and how to fix them