FAQ

Where do I set the idempotency key on the create call?

As an idempotency_key field in the JSON request body — it is a snake_case body field, not an Idempotency-Key header. The only request headers you set are X-API-Key and Content-Type. Derive idempotency_key from your own order id so it is reproducible; a retried create then returns the existing invoice instead of opening a second one. A fresh UUID generated at send time breaks the dedup on the retry.

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How to integrate a crypto checkoutHosted or self-hosted, fulfilled off the verified webhook Guides questionsFrequently asked questions drawn from the halfin guides pages. Each one links to a standalone answer.Can a customer charge back a crypto payment?No — not in the card sense. A card chargeback is a forced reversal initiated by the issuing bank, who can pull settled funds back out of your account…Can a leaked API key drain my balance the way a stolen hot-wallet key would?Only if it is the wrong key and your process allows it. A read-only or invoicing-scoped key cannot initiate a payout at all. A leaked payouts-scoped key…Can halfin cash my USDC out to a bank account?No. halfin is digital-asset payment infrastructure, not a fiat off-ramp — it does not sell USDC to a bank account. The USDC you collect sits in a balance…Can halfin convert my crypto balance to dollars in a bank account?No. Every conversion is asset-to-asset and stays on-chain — for example native SOL into USDC, or ETH into USDT. halfin is not a fiat off-ramp and does not…Can halfin convert my crypto to fiat and send it to my bank?No — halfin does not cash out to a bank. It converts between the crypto assets you hold on the platform, including settling volatile assets into a…Can halfin pay affiliates out to a bank account?No. A payout sends a crypto asset to a crypto address; halfin has no fiat off-ramp and does not move money to a bank. Balance conversion can rebalance…Can I accept both native ETH and ERC-20 tokens like USDC or USDT?Yes. 'Ethereum' covers native ETH and ERC-20 tokens on the same network, and halfin treats each asset as its own settlement rail. You choose which to…Can I auto-charge a customer's wallet every month like a saved card?No, and no crypto payment system can for a self-custody wallet — a wallet does not delegate standing authority to pull funds the way a card network lets a…Can I avoid network fees entirely?No — any transaction on a public blockchain pays the network for block space; that is how the chain is secured. What you can do is choose the rail…Can I build my integration before KYB is complete?Yes — and you should. Verification gates live transacting, not development. Use the sandbox to create invoices, simulate payments, and exercise your…