# Overview

Kaito provides **API-based connectivity** as a **payment rail** to move value across regions and rails:

- **FIAT <-> FIAT**
- **FIAT <-> CRYPTO**
- **CRYPTO <-> FIAT**
- **CRYPTO <-> CRYPTO**


You integrate once with the Kaito API, and Kaito handles routing, provider selection, fallbacks, and settlement orchestration (where applicable).

## Key concepts

- **railType**: declares the flow type (FIAT_FIAT, FIAT_CRYPTO, CRYPTO_FIAT, CRYPTO_CRYPTO).
- **Quote**: locks pricing and routing for a short time window.
- **Execution plan**: optional multi-step plan derived from a quote.
- **Payment / Payout**:
  - **Payment**: typically used for CRYPTO_CRYPTO or FIAT_CRYPTO flows.
  - **Payout (off-ramp)**: used for CRYPTO_FIAT or FIAT_FIAT flows.
- **Webhooks**: receive asynchronous updates for state changes.
- **Idempotency-Key**: safely retry create endpoints.
- **X-Trace-Id**: required for support and troubleshooting.