FastSpring for WHMCS

FastSpring for WHMCS lets hosting providers accept payments through FastSpring while keeping WHMCS invoices, services, subscriptions, and renewals in sync.

The module supports one-time purchases and recurring subscriptions across common WHMCS billing cycles. It uses your configured FastSpring catalog product paths for each billing interval, so the correct FastSpring subscription plan is selected from the WHMCS invoice.

Built for WHMCS businesses that want FastSpring checkout support without manually reconciling every payment, refund, renewal, or subscription event.

Key Features

FastSpring popup checkout integration for WHMCS invoices
One-time product payment support
Subscription billing for monthly, quarterly, semi-annually, annually, biennially, and triennially plans
Setup fee and invoice credit handling
WHMCS invoice total matching at checkout
Automatic subscription ID mapping back to WHMCS services
Automatic renewal payment handling through FastSpring webhooks
Full and partial refund support from the WHMCS admin invoice page
Manual subscription cancellation support from WHMCS
Product path validation to help prevent incorrect FastSpring catalog configuration
Webhook signature verification for secure callback processing

Supported Billing Scenarios

One-time product purchases
Monthly subscriptions
Quarterly subscriptions
Semi-annual subscriptions, billed every 6 months
Annual subscriptions, billed every 12 months
Biennial subscriptions, billed every 2 years
Triennial subscriptions, billed every 3 years
One-time product plus subscription invoices
Subscription invoices with setup fees
Subscription invoices with credits or discounts
Full refunds
Partial refunds
Manual subscription cancellation from WHMCS
Automatic renewal payment processing through FastSpring webhooks

How It Helps

WHMCS creates the customer invoice.
The customer pays through FastSpring popup checkout.
FastSpring sends webhook events back to WHMCS.
The module marks invoices paid, maps subscription IDs, and keeps renewal billing connected.
Future FastSpring subscription charges can automatically mark WHMCS renewal invoices as paid.

Requirements

Active WHMCS installation
Active FastSpring account
FastSpring API credentials
FastSpring webhook configuration
FastSpring catalog products for each billing interval you want to support

System Requirements

WHMCS 8.10 - 9.x
PHP 8.1 / 8.4
Requires ionCube Loader Version 15.0 or greater

Important Notes

FastSpring product paths are case-sensitive. The product paths configured in WHMCS must exactly match the product paths configured in your FastSpring catalog.

For recurring billing, each FastSpring catalog product should be configured with the correct subscription interval inside FastSpring. WHMCS selects the product path, while FastSpring controls the actual renewal schedule for that product.

Example product paths include monthly-sub, quarterly-sub, semiannual-sub, annual-sub, biennial-sub, triennial-sub, and whmcs-item.

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Version Compatibility

Compatible with WHMCS v9.0

Full Version Compatibility

All versions of WHMCS v9.0
All versions of WHMCS v8.13
All versions of WHMCS v8.12
All versions of WHMCS v8.11
Selected versions of WHMCS v8.10
8.10.0

Support for this product

The best place to start if you need help with a specific product is to contact the developer. All WHMCS Marketplace developers have both a website and support URL listed.

Visit Website Contact Support

Developed By Hostorigins

Changelog

v2.0 Released June 30th, 2026

Latest Version

This release introduces major improvements to the FastSpring for WHMCS gateway module, with stronger support for subscriptions, invoice total matching, refunds, and WHMCS service synchronization.

Added

Added support for multiple FastSpring subscription billing intervals:
Monthly
Quarterly
Semi-annually, billed every 6 months
Annually, billed every 12 months
Biennially, billed every 2 years
Triennially, billed every 3 years
Added separate WHMCS gateway settings for each FastSpring subscription product path.
Added FastSpring product path validation before checkout.
Added automatic subscription ID mapping from FastSpring back to WHMCS services.
Added support for subscription ID mapping from payment events and subscription events.
Added support for automatic renewal invoice payment matching through FastSpring webhooks.
Added support for full refunds from the WHMCS admin invoice page.
Added support for partial refunds from the WHMCS admin invoice page.
Added webhook signature verification support.
Added improved checkout debug logging for invoice amount, product paths, billing cycles, and expected checkout total.

Improved

Improved checkout amount calculation to better match the WHMCS invoice total.
Improved support for invoices with setup fees.
Improved support for invoices with credits or discounts.
Improved handling for subscriptions where the first payment amount is different from the recurring renewal amount.
Improved billing cycle detection from WHMCS invoice items and invoice date ranges.
Improved FastSpring catalog product selection based on WHMCS billing interval.
Improved subscription cancellation handling from WHMCS.
Improved error messages when FastSpring product paths are missing or incorrectly configured.
Improved FastSpring API error handling and logging.

Fixed

Fixed partial refunds incorrectly triggering full refunds.
Fixed recurring products using the wrong FastSpring billing interval in some cases.
Fixed semi-annual and biennial billing cycle mapping.
Fixed checkout totals not matching WHMCS invoice totals when credits were applied.
Fixed setup fees being missed from some checkout total calculations.
Fixed subscription IDs not always being populated in WHMCS after payment.
Fixed subscription mapping being skipped when duplicate payment webhooks were resent.
Fixed FastSpring product path case-sensitivity issues being difficult to diagnose.

Notes