Payment Gateway Integration: Stripe, PayPal, Crypto, and Beyond

Payment processing is where hosting billing meets real money. Get it right, and clients pay seamlessly. Get it wrong, and you lose revenue to failed transactions, unsupported currencies, and checkout friction.

Billing platforms typically take one of two approaches: they either hardcode a few popular gateways, or they offer a plugin marketplace where third-party developers build gateway integrations of varying quality and maintenance status.

FluxBilling does something different. Every payment gateway is a visual plugin — a configurable flow built with the same drag-and-drop editor used for provisioning automation. This means gateway behavior is transparent, modifiable, and extensible without writing code.

The Plugin-Based Gateway Architecture

Traditional billing platforms compile payment gateway logic into their core codebase. When a provider changes their API, you wait for the billing vendor to release an update. When you need a regional gateway, you hope someone has written a module for it.

FluxBilling''s approach separates gateway logic from the application core:

• Each gateway is a JSON-defined plugin with its own connection settings, flows, and webhook handlers
• The Flow Executor runs gateway operations node-by-node, executing API calls, conditions, and data transforms
• The Gateway Registry manages available gateways with priority ordering, currency support, and capability flags
• Connection management handles authentication, API keys, and mode switching (test/live)

This architecture means adding a new gateway does not require a software update. It requires a plugin definition and its operational flows.

Currently Supported Gateways

The following gateways are available out of the box in FluxBilling today:

Stripe

Stripe is the primary card payment gateway for most hosting providers. FluxBilling''s Stripe integration covers the full payment lifecycle:

• Checkout sessions — Redirect clients to Stripe''s hosted checkout for PCI-compliant card collection
• Payment intents — Handle the complete payment flow including 3D Secure authentication
• Refunds — Process full or partial refunds directly from the admin panel
• Webhooks — Real-time notifications for payment success, failure, disputes, and refund events
• Multi-currency — Process payments across Stripe''s wide range of supported currencies (see stripe.com for the current list)
• Saved payment methods — Clients can save cards for faster future payments
• Test and live modes — Switch between Stripe test and production environments with a toggle

PayPal

PayPal is essential for clients who prefer wallet-based payments:

• Checkout flow — Redirect to PayPal for payment approval and capture
• Multi-currency — Support for PayPal''s list of supported currencies (see paypal.com for the current list)
• Saved payment methods — PayPal account linking for recurring payments
• Refunds — Full refunds with reason tracking
• Webhooks — Event handling for payment completion, cancellation, and refund processing
• Sandbox mode — Full testing environment with PayPal''s sandbox accounts

CoinGate

For cryptocurrency payments, CoinGate provides a bridge between traditional billing and crypto:

• Multiple cryptocurrencies — Accept Bitcoin, Ethereum, and other coins supported by CoinGate
• Fiat settlement — Receive payouts in your preferred fiat currency regardless of which crypto the client pays with
• Automatic conversion — No cryptocurrency management required on your end

Bank Transfer

FluxBilling includes a built-in bank transfer gateway for providers who want to accept manual bank payments:

• Configurable bank details — Display your IBAN, SWIFT, and account information to clients at checkout
• Invoice matching — Match incoming bank transfers to outstanding invoices
• Manual confirmation — Admin marks payment as received when the transfer clears

On the Roadmap

Several additional gateways are planned for future releases. Check the FluxBilling roadmap or release notes for the most current status. Providers mentioned for future integration include Mollie, GoCardless, Paddle, and Square, among others. Availability is not guaranteed and timelines may shift.

Extensible Beyond the Built-In List

Because FluxBilling''s gateways are visual plugins rather than hardcoded modules, any payment provider with an HTTP API can be integrated without waiting for a platform release. If your preferred regional gateway is not in the built-in list, you can build it using the visual plugin editor — the same editor used for provisioning flows.

Typical steps for building a custom gateway plugin:

1. Create a connection in the plugin editor with the gateway''s base URL and authentication method
2. Build flows for the core operations: checkout session creation, webhook handling, and refund processing
3. Map the gateway''s response fields to FluxBilling''s internal payment record format
4. Test in sandbox mode with the gateway''s test credentials
5. Enable the gateway in production

This approach is how every built-in gateway is implemented. There is no hidden "core" gateway logic — what you see in the visual editor is exactly how payments flow.

How the Visual Flow Builder Works

Each gateway operation (create checkout, process webhook, issue refund) is a visual flow:

1. Start node — Triggered by an event (client clicks "Pay", webhook received, admin clicks "Refund")
2. HTTP request nodes — Make API calls to the payment provider with dynamic field mapping
3. Condition nodes — Branch based on API response (success? error? 3DS required?)
4. Transform nodes — Map response data to FluxBilling''s internal format
5. End node — Return the result (redirect URL, success confirmation, error message)

For example, a Stripe checkout flow looks like:

1. Start: Client initiates payment
2. HTTP POST: Create Stripe Checkout Session with line items, currency, and success/cancel URLs
3. Condition: Was the session created successfully?
4. Yes: Extract session URL, redirect client
5. No: Log error, show payment failure message

Each node is configurable through the admin panel. If a provider changes an API endpoint or adds a new parameter, you update the flow directly — no code changes, no waiting for a patch.

Gateway Configuration for Admins

Setting up a payment gateway in FluxBilling:

1. Install the gateway plugin from the visual plugin library
2. Configure connection settings — API keys, webhook URLs, mode (test/live)
3. Set gateway properties — Display name, priority order, supported currencies, transaction limits
4. Test — Process a test payment in sandbox mode
5. Enable — Make the gateway available at checkout

Admins can manage gateway priority to control which options appear first at checkout. For example, you might prioritize Stripe for card payments and show PayPal as a secondary option.

Multi-Currency Gateway Support

Payment gateways and multi-currency billing work together in FluxBilling:

• Each gateway declares which currencies it supports
• At checkout, only gateways supporting the invoice currency are shown
• Currency conversion happens at the billing level, not the gateway level
• Gateway-specific currency formatting is handled automatically

This prevents the common problem where a client in Japan sees a gateway button, clicks it, and gets an error because the gateway does not support JPY for that merchant account. In FluxBilling, that button simply would not appear.

Webhook Handling

Webhooks are critical for payment reconciliation. When a client pays, the gateway sends a webhook notification to FluxBilling confirming the transaction. FluxBilling''s webhook system:

• Verifies signatures — Each gateway''s webhook verification is handled in its plugin flow
• Processes events — Payment completed, payment failed, refund issued, dispute opened
• Updates records — Invoices are marked paid, services are activated, and email notifications are sent
• Logs everything — Full webhook payload logging for debugging and auditing

Why Plugin-Based Gateways Matter

The traditional approach to payment gateways creates vendor lock-in. You depend on the billing platform vendor to support your preferred gateway, update it when APIs change, and fix bugs when payments fail.

FluxBilling''s visual plugin approach shifts control to you:

• Transparency — You can see exactly what API calls the gateway makes
• Customizability — Modify flow behavior without waiting for a vendor update
• Extensibility — Build integrations for any gateway with an API
• Independence — Your payment processing is not locked to the billing vendor''s development roadmap

For hosting providers accepting payments globally, this flexibility is the difference between "we support a fixed list of gateways" and "we can add whatever your clients need."

Start your free trial to explore the payment gateway system. All built-in gateways are included in every plan at no extra cost.

Stripe, PayPal, CoinGate, Mollie, GoCardless, Paddle, Square, and any other third-party product names mentioned in this article are trademarks of their respective owners. FluxBilling is not affiliated with or endorsed by any of these companies. The list of supported gateways reflects FluxBilling''s state as of February 2026 and may change over time. Roadmap items are not guaranteed and timelines may shift. Third-party provider features and currency support are based on publicly available documentation and may differ from current capabilities — verify details directly with each provider.