SDK Overview
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A lightweight JavaScript SDK that allows you to embed secure payment and card-update experiences directly into your website, without handling sensitive financial data on your servers.
The Web SDK powers two core components:
Checkout Form SDK → Embedded payment form for subscription & one-time purchases
Card Update SDK → Allows existing subscribers to update their saved credit cards
Both components are fully PCI-compliant, mobile-responsive, and work seamlessly with Zotlo’s billing engine.
The SDK enables you to:
Accept subscription and one-time payments
Use plan-level pricing, trials, country-based currency
Receive webhook notifications for all transactions
Customize the form’s design using the style config
Let subscribers replace their payment card securely
Trigger 3D Secure flows when needed
Continue the subscription lifecycle without interruption
Through SDK event hooks:
onLoad
onSubmit
onSuccess
onFail
onInvalidForm
To initialize any checkout or card-update flow, you need:
A short-lived, auto-generated token used to start the SDK flow.
You can both live and sandbox keys in: Zotlo Dashboard → Developer Tools → Checkout SDK
Your backend generates a Checkout Token using API Keys
You pass this token to the SDK in your web application
The SDK renders a PCI-compliant payment form
User completes the payment → SDK triggers callbacks
Zotlo sends webhook events to your server (optional but recommended)
All modern browsers supported
Fully responsive mobile & tablet layouts
Works in single-page apps and server-rendered sites
SDK handles all card data — your servers never touch it
Fully PCI-DSS compliant
Secure 3D Secure (3DS) flows handled automatically
Sensitive fields are encrypted in-browser using Zotlo’s secure payment layer
Use the SDK if you want:
Embedded checkout on your own site
Zero PCI burden
Fully controlled UI/UX
Dynamic user-targeted checkout flows
Card update flows without exposing card info
Conversion-optimized payment experience
If you prefer redirect flows instead of embedded forms, consider Hosted Checkout instead.
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