REST API
The Zenith Payments Merchant API is the server-to-server integration surface for merchants who need backend control over payments, refunds, preauthorisations, customers, tokenised payment instruments, sessions, and related operations.
Use this section for integration guidance. Use /openapi for the full endpoint, schema, and example reference.
When to use the REST API
Use the REST API when your integration is primarily backend-driven.
Typical examples include:
- creating and retrieving payments
- creating refund requests and checking refund status
- managing preauthorisations
- creating or updating customers
- working with tokenised payment instruments
- creating secure sessions for Hosted Checkout
- running reconciliation or operational checks
If your main goal is to launch a hosted payment experience from your website or app, start with Hosted Checkout instead. If you want a hosted payment link with minimal integration effort, use Payment Links.
What the API covers
The Merchant API supports a broad set of merchant operations, including:
- payments
- preauths
- refunds
- customers (customer entities registered with Zenith Payments)
- sessions
- tokenisation and proxies
- batch payments
- request-to-pay flows
- diagnostics
This section does not try to repeat the full API reference. Its purpose is to explain how the API fits into a real integration and how to use it safely.
How to use this section
Use the pages in this section for guidance:
- Authentication — how Merchant API access works and how credentials should be handled
- Sessions and Hosted Checkout — how backend-created sessions fit into plugin-based checkout
- Common API Patterns — practical patterns for safe, maintainable integrations
- Refunds — how refund request flows work at a practical level
- Payment Methods — for conceptual detail on what each method is and when to use it, see /docs/resources/payment-methods. For field-level contracts on
/v2/cardproxies,/v2/proxies, and/v2/sessions, see/openapi. - API Reference — full generated reference at
/openapi
API Reference
The complete endpoint and schema reference is available at:
Use /openapi when you need:
- exact paths
- request bodies
- response schemas
- examples
- status codes
- field-level detail
Use the pages in this folder when you need:
- guidance
- integration patterns
- trust boundaries
- product-level context
Relationship to Hosted Checkout
Hosted Checkout and the REST API are related, but they serve different roles.
Hosted Checkout
Use Hosted Checkout when:
- the browser launches checkout
- Zenith hosts the payment UI
- your frontend uses the JavaScript Plugin
- your backend supports the flow with trusted session and validation logic
- securely collecting payment details without touching sensitive data
REST API
Use the REST API when:
- your backend is the primary integration surface
- you need direct operational control
- you want to create, query, or manage merchant-side resources programmatically
A typical integration may use both:
- REST API for backend operations
- Hosted Checkout for browser checkout launch
Recommended reading order
For most backend-led integrations, the best order is:
Summary
The REST API is the backend integration surface for Zenith Payments.
Use this section to understand how the API fits into your system, how to handle it safely, and how it works alongside Hosted Checkout. Use /openapi for the complete technical reference.