Helpful Notes

Plain-language explanations for common questions about wallets, invoices, payments, and privacy.

These notes are meant to help you make safe choices and understand what CryptoZing can and can’t access. If a page or email ever asks for a seed phrase or private key, stop — that’s never required.

Wallet & Security

Extended public keys (xpub / zpub): what they are and how we use them

CryptoZing asks for a BIP84 account extended public key (usually zpub or xpub) so it can generate a unique receiving address per invoice and watch for on-chain payments.

What is an xpub/zpub?
It’s a receive-only key that lets software derive many Bitcoin addresses for a single wallet account. Different wallets label them as xpub or zpub, but they’re both extended public keys.
Why do we ask for it?
To generate a fresh address per invoice (better bookkeeping and less address reuse) and to automatically detect payments sent to those addresses.
What can’t it do?
An xpub/zpub cannot spend your bitcoin. It can’t sign transactions, move funds, or reveal your private keys.
What are the privacy implications?
Anyone who has this key can derive and monitor the addresses in that account. Treat it like sensitive data: don’t share it, and avoid posting screenshots or logs that include it.
Best practice (recommended)
Use a dedicated “Invoices” wallet or account for CryptoZing and share only that account’s xpub/zpub. This keeps invoicing activity separate from personal holdings, reduces address-linking exposure, and makes it easy to sweep funds to an exchange/off-ramp or cold storage.
What we will never ask for
CryptoZing will never ask for your seed phrase, private keys, wallet file, or for you to “send a test transaction” to unlock anything.

Why CryptoZing needs a dedicated receiving account

CryptoZing can reliably track invoice payments only when the account key you connect here is used for CryptoZing invoice receives and not for unrelated receives elsewhere.

What breaks automatic tracking?
If the same account also receives payments in another wallet app, from a shared QR, or from manually generated receive addresses, CryptoZing can no longer safely tell which receives belong to which invoices.
What do I still use my wallet app for?
You will use your wallet app to view balances, sweep funds, and spend from this account. CryptoZing only watches for invoice receives. The risky part is using the same account for additional receives outside CryptoZing.
What does unsupported configuration mean?
It means CryptoZing found evidence that this account is receiving funds outside the app, so automatic payment attribution is no longer reliable for new invoices on that account.
How do I fix it?
Connect a fresh dedicated account key and use that account only for CryptoZing invoice receives going forward.
Safest setup
Use one dedicated receive account or app for CryptoZing, then sweep or spend from a separate account or wallet. That keeps invoice receives isolated and easier to trust.

Importing your wallet account key (xpub / zpub)

To connect a wallet to CryptoZing, you copy your wallet’s account-level extended public key and paste it into Wallet Settings. This lets CryptoZing generate a unique receiving address per invoice.

Recommended: BlueWallet

  1. Create a new Bitcoin wallet (recommended: name it “CryptoZing Invoices”).
  2. Open that wallet, tap the menu (⋯), then choose Backup/Export.
  3. Copy the extended public key (often starts with zpub or xpub).
  4. Paste it into CryptoZing’s Wallet Settings.

Other wallets

  • Look for Account details, Wallet details, or Advanced → “Extended public key” / “Master public key”.
  • Make sure you’re exporting an account key, not a single receive address.
  • If your wallet supports multiple accounts, create a dedicated Invoices account and export the key for that account.

After you get paid

  • It’s normal to sweep funds to an exchange/off-ramp or cold storage to reduce volatility exposure.
  • CryptoZing never has custody and cannot send funds — any sweep/refund is a transaction you send from your wallet.

Advanced: importing a seed phrase (only if you insist on using an existing wallet and know what you're doing)

If you’re determined to keep a wallet that won’t export an xpub/zpub, you can import that wallet’s seed phrase into a wallet that can export one — but this is risky. Importing a seed phrase gives that app full spending access. Only do this if you understand the security tradeoffs.

Invoices

Why invoices use unique addresses

Each invoice gets its own receiving address so payments are easier to match and you avoid reusing addresses.

How the BTC rate is calculated

CryptoZing treats the invoice amount in USD as the source of truth and converts to BTC using a live BTC/USD spot rate.

  • Data source: we fetch a BTC/USD spot rate and may cache it briefly to avoid excessive rate lookups.
  • Conversion: BTC = USD ÷ (USD per BTC), rounded to 8 decimal places, (satoshi level accuracy).
  • In the unlikely event rates are unavailable: we fall back to the last known rate stored with the invoice.
  • Outstanding balance: Bitcoin payments can be split across multiple transactions. Until the confirmed total meets the invoice amount, we show the remaining amount due as the outstanding balance (full amount, remainder, or $0 when paid).

Example: Alice invoices Bob for $1,000. Bob sends $600 worth of BTC first. Once that payment confirms, the invoice shows Partial and an Outstanding balance of $400, and the QR/BIP21 updates to the remaining $400. When Bob sends the rest, the invoice becomes Paid and the outstanding balance becomes $0.

Payments

Pending vs confirmed

Bitcoin payments may appear quickly but can take time to confirm. CryptoZing tracks what’s detected on-chain and updates invoice status once confirmations meet the configured threshold.

Partial payments

If a client pays in multiple transactions, CryptoZing records each payment and shows what’s still outstanding.

  • Invoices move from Pending (detected) to Partial (some confirmed) when more is still due, then to Paid when the confirmed total meets or exceeds the invoice amount.
  • Each payment’s USD value is credited using the BTC/USD rate at the time we detected it, so later volatility doesn’t change what was credited.
  • The QR/BIP21 always targets the current outstanding balance so clients can finish payment without overpaying.

Overpayments

If a client sends more than the invoice amount, CryptoZing records the full amount received. The invoice will still be marked paid once the confirmed total meets or exceeds the invoice amount.

Overpayments are treated as gratuities by default. If it was accidental, coordinate with your client to refund or apply the surplus as a credit.

Example: Alice invoices Bob for $1,000. Bob accidentally sends $1,200 worth of BTC. CryptoZing records the full payment and marks the invoice paid. If Alice wants to refund the extra, she sends that transaction from her own wallet — CryptoZing cannot send funds on her behalf.

CryptoZing does not send funds and never has custody of your bitcoin. Any repayment/refund is your responsibility to send from your own wallet.

Privacy

Public invoice links

Public invoice links are designed for sharing with a specific client. However, anyone with the link can view it — share thoughtfully.