Outside Shopify, most ecommerce platforms treat the payment gateway as a plugin and do not penalize you for choosing one. That makes the gateway decision a pure cost and features question. This page covers the platforms we are asked about most, which gateways connect, and how switching works on each.
Platform by platform
| Platform | Bundled option | Platform fee for external gateway | External gateways with native or official support |
|---|---|---|---|
| Magento Open Source / Adobe Commerce | Braintree (bundled extension) | None | Authorize.net (official), Stripe, PayPal, NMI, accept.blue, Fluidpay (native and AIM emulator) |
| BigCommerce | PayPal-powered | None on any plan | Authorize.net, Stripe, Square, Braintree, NMI-based providers, many processor gateways |
| Ecwid (Lightspeed) | Stripe-powered | None | Authorize.net, Square, PayPal, Stripe, others by region |
| OpenCart | None; modules included | None | Authorize.net, NMI, accept.blue, Fluidpay, Stripe, PayPal via core modules and marketplace extensions |
| Volusion | Volusion Payments (historically) | None | Authorize.net and other gateways via admin |
| WordPress with form or membership plugins (Gravity Forms, WPForms, MemberPress, GiveWP) | Varies by plugin; usually Stripe or PayPal | None | Authorize.net on most; NMI and others via add-ons |
Confirm the current extension for your platform version before boarding; plugin support changes, and Payflow in particular is being dropped by several platforms in 2026.
Bundled vs merchant account gateway
The arithmetic is the same on every platform without a surcharge, and it is worked through on the gateway pricing page. Short version: bundled providers (Stripe-powered, PayPal-powered, Braintree) charge 2.6% to 2.9% plus a per-item fee with no monthly; a merchant account gateway charges $10 to $25 a month plus a per-item fee with processing on interchange-plus. Crossover is around $10,000 to $15,000 a month. Above that the merchant account saves 0.4% to 0.8% of volume, more with international or commercial card mix.
Choosing among the merchant account gateways
| Need | Gateway |
|---|---|
| Widest plugin history, direct sign-up, published pricing | Authorize.net |
| Multiple stores or MIDs, broad vertical software integrations | NMI |
| Modern interface, invoicing, Level 3, Amex routing | accept.blue |
| Legacy cart that only speaks Authorize.net AIM; dual pricing online | Fluidpay |
All four connect to the platforms above and to a merchant account priced on interchange-plus. Comparison detail is on the Authorize.net alternatives page.
PCI on self-hosted platforms
Magento, OpenCart and WordPress stores are usually self-hosted, which means the store owner is responsible for the server. Use a gateway integration with hosted fields or a hosted page so card data never reaches that server; the store then qualifies for SAQ A regardless of how the server is maintained. A direct-post integration on a self-hosted store is the configuration most likely to fail a PCI review. The hosted page and PCI guide explains the options.
Switching gateways, generically
- Install the new gateway’s extension. Configure in sandbox or test mode. Place test orders.
- Enable live alongside the old gateway. Run real low-value orders with each card brand. Refund.
- Migrate stored cards and subscriptions if any: encrypted vault export from the old gateway, import to the new, remap customer tokens, recreate schedules after the last old-gateway billing run.
- Make the new gateway default. After a week of clean settlement, disable the old one. Keep it installed until subscriptions have renewed once.
- Close the old gateway account and, if you changed processors, the old merchant account.
Platform-specific notes:
- Magento. Test on a staging copy first; extension conflicts are common. Braintree’s bundled extension can stay installed for PayPal wallet acceptance.
- BigCommerce. Gateway settings are in the control panel; changes apply immediately. Enable the new provider and disable the old in the same session after testing.
- Ecwid. Payment settings are per-store in the control panel; test with a $1 product.
- OpenCart. Module order controls which gateway shows first at checkout; set the new one first.
- Volusion. Gateway credentials are in the payment settings; keep the old credentials until the first live settlement clears.
- WordPress plugins. Each form or membership plugin has its own gateway add-on; a site with three plugins may need three configurations.
What we do
Confirm the integration for your platform, board the gateway on a merchant account priced on interchange-plus, coordinate the vault export, and stay on the call for the cutover. One bill, month to month, and a person to call when a plugin update breaks checkout at 9pm.