Finsyncio API Documentation

REST API reference, SDK guides, webhook integration, and KYC/KYB flows for embedding payments, lending, and cards into your vertical SaaS platform.

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From API key to first ACH payment in 15 minutes. KYC verification included.

Every endpoint, parameter, response schema, and error code.

Node.js, Python, and Go client libraries. Ruby in beta.

HMAC-SHA256 signed event delivery. payment.cleared, loan.funded, card.authorized.

Onboard individuals and businesses with automated identity and business verification

Initiate, track, and handle payment webhooks

Underwriting, disbursement, and servicing flow

Issue virtual and physical cards with spend controls

Idempotency-Key header behavior, 24-hour dedup window, and safe retry patterns for payment mutations

Test cards, magic amounts, and simulated failures