Zahlo Merchant Developer Docs - Zahlo Merchant Developer Docs

Zahlo gives merchants one API for checkout, payments, subscriptions, invoices, payment links, and commerce integrations. Use hosted checkout when you want the fastest launch, or use in-page checkout and the SDK when the payment experience must stay inside a custom website.

Choose your path

Goal	Start with
Launch a first payment	Quickstart
Add checkout to a website	Checkout guide
Sell through a shareable URL	Payment links
Start recurring billing	Subscriptions
Integrate an online store	WooCommerce
Explore every endpoint	API Reference

Common use cases

Use case	Building blocks
Online store	Catalog, line items, dynamic methods, shipping, tax, webhooks, fulfillment
SaaS billing	Customers, recurring prices, trials, invoices, retries, portal, subscriptions
Invoices and sales	Payment links, hosted checkout, customer metadata, refunds
Custom checkout	Checkout sessions, in-page SDK, appearance, locale, allowed origins
WordPress store	WooCommerce integration, server-side correlation, signed events

Integration principles

Keep merchant API keys on your server.
Use short-lived client tokens for browser checkout state.
Treat webhooks as the source of truth for fulfillment and subscription state.
Send an idempotency key when retrying create requests.
Never collect or store raw card data in your application.