Guides
Test mode
Test networks, test keys, a button that pays. Free and unlimited.
Test mode is a second set of books next to live. Its own keys, invoices, customers and webhooks. Nothing in it touches live.
| Test | Live | |
|---|---|---|
| Keys | sk_test_… | sk_live_… |
| Bitcoin | testnet4 | mainnet |
| USDC, USDT | Base Sepolia, Ethereum Sepolia | Base, Arbitrum, Optimism, Ethereum (USDT on Arbitrum and Optimism is USDT0) |
| Receipt numbers | TEST-NW-2026-000001 | NW-2026-000001 |
| Emails | Your team only | Your buyers |
| Counts toward your plan | Never | Paid invoices |
In test mode, letters go only to your team's addresses: the members and your support email. A receipt or a refund link for anyone else is held, not sent. To see what a buyer gets, pay a test invoice with your own email.
Simulate a payment
Every test invoice page has a Simulate payment button. Choose full, short or over, and the invoice moves exactly as it would on-chain: Arriving, then Paid (or Underpaid, Overpaid), then a receipt and your webhooks.
- Full — the invoice is paid and fulfilled.
- Short — it waits as Underpaid until the rest arrives or it expires.
- Over — it's paid, and the extra is shown for you to refund.
From code, the same button is an API call — find simulate in the API reference.
Real test coins
You can also pay a test invoice for real with testnet coins from any public faucet. The watcher reads test networks the same way it reads mainnet.
Never send mainnet money to a test invoice. Test addresses are made for test networks.