# Test a crypto checkout without mixing test and live payments

> Coinvay’s merchant Sandbox provides an interactive checkout preview and separate Base Sepolia test payments. Preview states are simulated; real testnet payments are verified on-chain and stored separately from live invoices, revenue and plan usage.

Publisher: Coinvay | Published: 2026-10-27 | Updated: 2026-10-27 | Category: Developer guides
Canonical: https://coinvay.com/articles/crypto-checkout-testnet-sandbox

Explore checkout previews and real Base Sepolia payments in Coinvay’s separate merchant Sandbox without changing live revenue.

## Use preview for design and customer support

Open Sandbox in the merchant workspace and choose Checkout preview to explore the currency, payment-method, manual-instruction, waiting, success, expired and failure screens. The preview uses your merchant branding and sends no transaction. It is useful for checking terminology or explaining the flow to staff, but a simulated confirmation must not be used as evidence that a wallet or network integration works.


## Use testnet mode for transaction verification

Save a Base Sepolia receiving address in the separate sandbox settings. Select test ETH or test USDC, choose a small token amount and confirm that you will use only testnet tokens. Coinvay creates a time-limited test checkout with an exact adjusted amount. A sender approves the transfer in their wallet, or pays manually and submits its hash. Verification checks the chain, successful receipt, canonical block, recipient, asset, exact quantity and required confirmations.


## Know the isolation boundary

For example, a merchant can complete a test USDC checkout without consuming a live invoice allowance or creating a live sale. Optional sandbox webhooks use a different URL and signing secret, carry livemode false and are sent manually from test history. Keep the page open for polling or reopen it to verify a timely transfer by hash. Sandbox management requires an interactive session; live merchant API keys and the downloadable commerce kits are not automatically connected to these test endpoints.


## Practical checklist

- Label test wallets and obtain free tokens for Base Sepolia, not a similarly named network.
- Verify the displayed exact amount, receiving address and three-confirmation requirement.
- Keep test webhooks and fulfillment effects outside the production order system.

## Questions and answers

### Can a preview success screen count as a test payment?

No. It is an explicitly simulated visual state. A real testnet checkout must be confirmed using blockchain evidence.

### Will test payments appear in live revenue or invoice usage?

The new sandbox flow uses separate records and excludes them from live payment reporting and plan invoice usage.

## Sources and further reading

- [Coinvay merchant API documentation](https://coinvay.com/docs)

## Related guides

- [How to integrate a crypto payment API without trusting the browser](https://coinvay.com/articles/crypto-payment-api-integration)
- [Create crypto invoices with the Coinvay API](https://coinvay.com/articles/create-crypto-invoices-with-api)
- [Verify Coinvay crypto payment webhook signatures](https://coinvay.com/articles/verify-crypto-webhook-signatures)

Published by Coinvay with AI-assisted drafting. Product claims were checked against the implementation and linked primary sources. Provider facts and pricing can change; verify the current terms before choosing a service. Examples are illustrative, not customer results. No ranking or AI citation is guaranteed.