Ethereum
Base
Optimism
Arbitrum
Polygon
Avalanche
BNB Chain
ArcBuild better payments
SDKs for devs, checkout for customers
We handle the plumbing
SDKs, hosted checkout, and infrastructure — built for your team
One API call, one address
Set an amount and accepted tokens — get a deterministic address back instantly
Your checkout, all the way
Your own UI, or our hosted checkout page — live status, no polling
Straight to your recipients
Detected and routed on-chain straight to you — split if configured, never through us
Built by developers
For developers
We're developers too, so the SDK is typed, the errors are predictable, and there's no blockchain plumbing standing between you and shipping
Install the SDK
One package, zero blockchain plumbing on your side.
npm install @klappay/node
SDK highlights
Stop polling
Start streaming
Three long-lived SSE connections — one charge, your full webhook feed, or pending payouts — so your app always knows the moment something changes
Watch one charge
Live, start to finish
Subscribe to a single charge and get the full snapshot on connect, then every update the moment it happens — no polling for status.
One API
A growing suite of products
The Core API is the foundation — everything above it ships as a standalone product
Klap Core
LIVEKlap Core is the non-custodial payments API at the center of everything Klap ships. Create a charge, get a deterministic on-chain address back, and your customer pays directly into it — Klap only detects the transfer and routes the payout. No custody, no money-transmitter license, no counterparty risk at any step.
How it works
Install the Node SDK, create a client with your API key, and call charges.create() with an amount and accepted tokens. Await confirmation with a single Promise, or verify server-side with a signed webhook — the full walkthrough is in the Integration section above.
- Swap-to-pay
- Escrow
- Real-time status
- Analytics API
- Fee passthrough
- Wallet Trust
What we're building
Next products shipping on the same non-custodial rails
A few more ideas on the roadmap:
- Klap Give
- Klap Commerce
- Klap Payroll
- Klap Streams
The payment layer
Without the gatekeeper
Your funds don't need a middleman
Your developers don't need more workarounds
Custody
Others — Funds pass through the provider’s account before reaching you.
Klap — Never. Funds go straight to the on-chain split address.
Integration
Others — Hosted widget/iframe — you adapt your product to it.
Klap — Pure API. Your checkout, your design, your UX.
Split payments
Others — Bolted-on feature, usually gated or priced separately.
Klap — Native: a multi-recipient address ships with every charge.
Real-time status
Others — Manual polling or a single webhook, no native stream.
Klap — SSE + webhooks + charge.waitForConfirmation() in the SDK.
Sandbox
Others — Testnet-only when it exists — slow, brittle setup.
Klap — Simulate any charge event without touching a real chain.