Klap Docs

KlapNon-custodial crypto payments

Keep Liquidity Always Permissionless. A merchant creates a charge, the payer sends funds directly to a predicted on-chain address, Klap detects and distributes it — without ever holding the money itself. This site covers the REST API, the Node.js SDK, and the TypeScript types together, by resource.

How it works
Getting started
API Playground
Klap

How it works

The core model — predicted addresses, detection vs. settlement, why there's no refund API. Read this first.

Charges

Create a charge, accept multiple token/network pairs, wait for confirmation and settlement over SSE, list and audit.

Webhooks

Subscribe to charge and delivery events, verify inbound signatures, manage retries and rotation.

Sandbox

Trigger any charge event on demand — test your integration end to end without waiting for real on-chain activity.

Metrics

Query business metrics live — volume, fees, settlement — with no separate snapshot table to go stale.

Distributions

Pending payout splits and their live event stream.

Recipients

Register trusted payout addresses once, then reference them by id in a charge split — no raw address ever rides a charge request.

Networks & tokens

The current token/network matrix your API key can accept, read live instead of hardcoded.

Authentication

API keys, scopes, key rotation and revocation.

Real-time (SSE)

Live charge status without polling — how the stream works, and the polling fallback.

Errors

The typed error hierarchy across the REST API and the Node.js SDK.

AI assistants (MCP)

Let Claude, Cursor or any MCP client read charges, webhooks and metrics with your key — local, open source, read-only in live by default.

What this is ​

One doc, organized by resource — not three separate sites for the API, the Node.js SDK, and @klappay/types. Every resource page below covers all three together: the concept, the REST endpoints, the SDK methods, and the types, so you don't have to cross-reference three tabs to build one integration.

For the interactive request builder (try-it, auth, generated curl), use the API Playground — that stays a separate tool on purpose, this site is for reading, not for firing live requests.

Not sure where to start? How it works covers the non-custodial model in 5 minutes, Getting started covers installing the SDK and creating your first charge, and Build a checkout flow walks the whole thing end to end — charge, hosted checkout, webhook, confirmation.

Klap API, Node.js SDK and types reference.

MIT — Klap