Blog
2026-10-28
A signup form can tell an attacker which emails have accounts, and an unverified account can end up holding a payout address. How Klap App and Klap Link moved to email-first signup, and the checklist behind it.
2026-10-27
A transfer you can see on-chain isn't final yet. How Klap picks a confirmation depth for each network, from 1 block on Arc to 150 on Polygon, and how the checkout turns that wait into three honest steps.
2026-10-26
Circle can freeze a USDC address and Tether can freeze a USDT one. What each token actually blocks, why a single frozen recipient can stall a whole split, and how Klap checks before a payer sends a cent.
2026-10-14
Arc is live in Klap on the official 0xSplits contracts. What changes when USDC is also the gas token, why one confirmation is enough, and how to add Arc to a charge you already create.
2026-10-13
Klap Link is live. One link per service, a monthly retainer that invoices itself, and every payment lands in your own wallet. A no-code walkthrough for freelancers, consultants and small studios.
2026-10-05
A hosted checkout page and a payment API answer the question of who owns the payment screen. Neither one answers where the money lands. How to pick between them, and why custody needs its own separate check.
Where to start when you're building USDC payments into your own product: the custody decision, the charge, the checkout, the events, the handler, splits and escrow, and testing. One page that maps the whole integration and links to the deep dive for each step.
2026-10-04
A payment webhook is a delivery attempt, not a receipt. How to make a retried, duplicated, or out-of-order crypto payment event change your books exactly once, with the guarantee living in database constraints instead of a lookup that races.
2026-09-23
No wire fees, no three-day hold, no volatility to hedge against. How to send a client an invoice, get paid in USDC straight to a wallet you control, and see the money the moment it lands — no code required.
2026-09-22
Not every charge should settle the instant payment is detected. How a per-charge, 1-of-1 Safe — released only by a signature Klap can't produce — lets funds wait on a business condition without anyone taking custody of them.
2026-09-21
A browser-extension wallet isn't a requirement for self-custodied crypto payments. How OTP-based identity plus linked-wallet approval lets a customer pay without ever installing MetaMask.
2026-09-20
Defining a split is the easy part. Distribution is a separate, permissionless on-chain step with its own failure states — what actually happens between a confirmed charge and a recipient actually getting paid.
2026-09-19
A USDC recurring billing system is not a crypto version of Stripe Billing — a self-custodial wallet can't safely become a standing debit order just because a customer connected it once. This is how to design the authorization model, the state machine, and the events underneath it properly.
2026-09-18
A customer sends USDC, the transaction confirms on Base, and the money lands in a wallet your business controls — not in a processor balance waiting on a withdrawal. That changes more than where a number appears on a dashboard; it changes who's responsible for it.
A wallet address on a checkout page is not a payment API — it's a static request for money with no idea whether it got paid. The real work starts after the customer sends USDC: detecting the transfer, matching it to a charge, and giving your backend a status it can act on.
2026-09-17
The two hard parts of a custom crypto checkout — turning a charge into what a payment screen needs, and talking to an injected wallet — already built, audited, and shipped as one npm package. Code for every step, from the first payload to a payer with three wallet extensions installed.
A payment link is just a URL until you ask who actually receives the money and when. How to back one with a real charge, route splits at creation instead of after the fact, and build the page around it yourself.
2026-09-16
A checklist for picking a Node.js crypto payment SDK — the custody question underneath everything else, whether it models a real payment lifecycle, and why a sandbox that can't trigger an underpayment isn't actually a sandbox.
A customer's wallet says the transaction succeeded. Your checkout is still spinning. Closing that gap means picking the right channel for the right job — SSE for the screen, webhooks for the business action — and never confusing the two.
2026-09-15
USDC settles in seconds for fractions of a cent — the blockchain isn't the bottleneck. What is: custody, integration time, and missing primitives, and what closing that gap actually looks like.
2026-09-14
Direct settlement isn't proven by a wallet address on a checkout page. What changes when a merchant's own destination receives funds first, and why detecting a transfer is a different job than holding it.
A hosted checkout page is the first compromise in a payment integration. How to treat crypto payment acceptance as infrastructure you own: create a charge, present a destination, and drive order state from verified events.
2026-09-13
Splitting a charge across a seller, a platform fee, and other recipients isn't hard math — it's making the allocation deterministic, observable, and enforceable without funds ever passing through a processor-controlled account.
Testing that a charge endpoint returns 200 isn't testing a payment integration. How to build a sandbox around the real charge lifecycle — duplicate events, out-of-order delivery, expiry, underpayment — using Klap's sandbox triggers.
2026-09-09
A crypto checkout should not ask customers to send funds to a shared wallet. Why per-charge deterministic addresses matter, and how to build charge state around them.
A webhook doesn't settle funds — it reports settlement that already happened on-chain. How the event flow works, what the payload should contain, and why signature verification and idempotency aren't optional.
2026-09-08
Custody isn't an implementation detail — it's the architecture of the financial relationship. A guide to what a non-custodial crypto payments API does, and how to evaluate one.
2026-09-07
A transaction hash isn't proof of payment. A backend checklist for verifying on-chain USDC settlement, designing event-driven fulfillment, and validating what wallets won't tell you.
