Developer Setup

Use this setup checklist before building any merchant or lender integration.

Environments

Surface	Sandbox	Production
Merchant BNPL APIs	https://gateway-sandbox.fundiin.vn	https://gateway.fundiin.vn
Lender webhooks	https://api-qa.fundiin.vn	https://api.fundiin.vn

Credentials

Fundiin provides credentials during onboarding.

Credential	Used for
Client-Id	Identifies the merchant, platform, or lender partner.
secretKey	Signs and verifies request bodies with HMAC SHA-256.
Portal access	Manages merchant operations, credentials, and transactions.

Shared primitives

These apply to both merchant and lender integrations.

Primitive	What to implement
HMAC signing	Sign outgoing requests and verify incoming callbacks. See Signature.
Idempotency	Retry safely without duplicate processing. See Idempotency.
Webhooks	Receive payment status, loan, and repayment events. See Webhooks and Callbacks.

Shared tools

Tool	Used for
Postman Guide	Build and test signed requests for either merchant or lender APIs.
HMAC Signatures	Generate HMAC request signatures across all integration surfaces.
Webhook Event Builder	Generate signed webhook payloads and cURL commands for merchant callbacks or lender notifications.
Idempotency	Retry safely without duplicate processing.

Surface tools

Tool	Used for
API Explorer	Explore merchant BNPL, tokenization, and lending API requests.
Lending APIs	Jump directly to lender loan lifecycle and repayment notifications.
Merchant Demo	Try the merchant BNPL checkout experience.
Test Instruments	Validate merchant checkout scenarios in sandbox.