Afterpay (Block) Buy Now Pay Later API
Afterpay (a Block company) buy now pay later REST API for e-commerce merchants to integrate installment payment checkout, allowing consumers to split purchases into 4 interest-free biweekly payments with instant approval, no hard credit check, and merchant receivables paid upfront while Afterpay assumes default risk, with coverage in Australia, New Zealand, US, Canada, UK (as Clearpay), France, Italy, and Spain. Enables AI agents to manage Afterpay checkout session for BNPL payment initiation automation, handle checkout token exchange for order confirmation automation, access consumer eligibility for BNPL qualification automation, retrieve order management for payment lifecycle automation, manage refund processing for BNPL reversal automation, handle webhook events for payment status automation, access merchant portal data for settlement reporting automation, retrieve order capture for authorization and capture automation, manage deferred payment for subscription BNPL automation, and integrate Afterpay with Shopify, WooCommerce, Magento, Salesforce Commerce, and headless commerce for end-to-end BNPL checkout automation.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
BNPL. Block/Square subsidiary. PCI-DSS, GDPR. Basic auth. AU/US/EU. Consumer payment data.
⚡ Reliability
Best When
An e-commerce merchant wanting AI agents to integrate Afterpay buy now pay later into checkout flow with 4-payment installment option and upfront payment from Block's BNPL platform across US, AU, UK, and European markets.
Avoid When
CHECKOUT IS REDIRECT-BASED: Afterpay checkout redirects consumer to Afterpay-hosted flow for authentication; automated inline checkout assumption without redirect creates integration failure; automated checkout must implement redirect/popup flow. ORDER TOTAL LIMITS APPLY: Afterpay has minimum ($35 US) and maximum ($2,000 US) order totals; automated BNPL for all order sizes creates AMOUNT_INVALID for out-of-range orders; automated must check order total eligibility before showing Afterpay. CURRENCY AND REGION MUST MATCH: Afterpay is region-specific with different domains (afterpay.com US, clearpay.co.uk UK); automated single global API endpoint assumption creates region mismatch; automated integration must use region-specific API URL and credentials. CAPTURE IS SEPARATE FROM CHECKOUT: Afterpay checkout creates authorization token; merchant must separately capture the payment; automated checkout-as-payment assumption creates authorized-but-not-captured orders that auto-void.
Use Cases
- • Adding Afterpay installment checkout to e-commerce product and cart pages from checkout agents
- • Processing Afterpay refunds for returned orders from order management automation agents
- • Receiving Afterpay order confirmation webhooks for fulfillment trigger automation agents
- • Integrating Afterpay into headless commerce checkout from payment orchestration agents
Not For
- • B2B invoice payment (Afterpay is consumer retail BNPL, not B2B net terms)
- • High-value single purchases over Afterpay limit ($2,000 USD consumer limit)
- • Markets outside covered regions (Afterpay operates in AU, NZ, US, CA, UK, FR, IT, ES)
Interface
Authentication
Afterpay uses HTTP Basic Auth (merchant ID + secret key) for API authentication. REST API with JSON. Melbourne, Australia HQ. Founded 2014 by Nick Molnar and Anthony Eisen. Acquired by Block (formerly Square) 2022 ($29B acquisition). Products: 4-payment installment, merchant checkout, merchant portal. SDKs: JS, iOS, Android. PCI DSS. GDPR (Clearpay UK/EU). Serves 100,000+ merchants, 20M+ customers. Competes with Klarna and Affirm for BNPL market.
Pricing
Melbourne AU. Block subsidiary ($29B acquisition 2022). Merchant fee 4-6%. Upfront merchant settlement.
Agent Metadata
Known Gotchas
- ⚠ CHECKOUT FLOW IS REDIRECT NOT EMBEDDED: Afterpay checkout redirects consumer to Afterpay-hosted authorization page; automated embedded inline payment form assumption creates integration failure; automated checkout must implement redirect to Afterpay URL with returnUrl and cancelUrl parameters
- ⚠ CAPTURE MUST FOLLOW CHECKOUT: Afterpay checkout creates authorized-only token; automated order fulfillment without explicit capture creates void-at-expiry authorization; automated must call capture endpoint with checkout token before fulfillment
- ⚠ ORDER AMOUNT LIMITS ARE REGION-SPECIFIC: Afterpay US minimum $35, maximum $2000; AU/UK have different limits; automated universal amount range creates AMOUNT_INVALID for out-of-range orders; automated must check region-specific limits
- ⚠ REGION-SPECIFIC API BASE URL: Afterpay US uses api.afterpay.com; UK uses api.clearpay.co.uk; AU/NZ use api.afterpay.com with AU credentials; automated single URL for all regions creates wrong-region authentication failure
- ⚠ WEBHOOK ORDER STATE MUST DRIVE FULFILLMENT: Afterpay payment confirmation delivered via webhook; automated synchronous confirmation after redirect creates race condition; automated fulfillment must be driven by APPROVED webhook event not redirect callback alone
Alternatives
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Scores are editorial opinions as of 2026-03-07.