Tor mode is on. Address and UTXO lookups will use the .onion endpoints in your settings.

For .onion addresses to actually resolve, this page must be loaded in Tor Browser (or a regular browser configured to route requests through a Tor proxy). A normal Chrome or Firefox cannot reach .onion addresses and the requests will fail at the network layer.

## Load wallet

Pick where the watch-only key (and optionally the UTXOs) come from. The Vault holds wallets at rest. The Scryer reads the same export and adds live balance and UTXO data on top. Manual paste is the catch-all for any wallet that exports an xpub, ypub, or zpub.

Pick from your computer

One click opens your operating system's file picker. The builder loads the file automatically.

Paste the JSON

Copy the file's contents into the box, then click Parse.

Watch-only JSON
Pick a wallet from this file

Paste the account-level mainnet extended public key (xpub, ypub, or zpub) of the wallet whose UTXOs you want to spend. Used only to derive addresses; it cannot sign.

Account xpub / ypub / zpub (mainnet)

## Wallet addresses

Addresses derived from the loaded extended public key. Use these to look up which addresses hold UTXOs in your watch-only tool (Scryer, mempool.space), then click + UTXO on the matching row to prefill a UTXO row with the right path. You only need to fill in txid, vout, and value.

Path | Address |
--- | --- | ---

usedhas had on-chain transactions before, even if the balance is now 0 freshno on-chain history, safe as a brand-new receive address

## UTXOs to spend

Add the unspent outputs you want to fund this transaction with. Get these from your watch-only tool (Scryer, mempool.space, an Electrum server you trust). The "path" column is the address index under the account, written as change/index (for example 0/3 for receive-chain index 3).

txid | vout | path | value (sats) |
--- | --- | --- | --- | ---

Total selected: 0 sats

## Recipient and fee

Recipient address Amount (sats)
Fee rate (sat/vB)
Set this to your target 2-block rate (check a fee oracle on a separate online device before using this offline tool).
Change path (default 1/0)

#### PSBT in plain language

A PSBT (Partially Signed Bitcoin Transaction, BIP-174) is a standard file format for a transaction that is being put together in steps.

One tool builds the unsigned shape: which coins to spend, who gets paid, how much fee. Another tool, kept offline with the seed, signs it. A third tool broadcasts the signed transaction to the network.

Hardware wallets, Sparrow, Electrum, and this prototype all speak the same PSBT format. You can hand it around as a base64 string, a .psbt file, or a QR code.

In this tool the Build tab makes the unsigned PSBT. The Sign tab takes a PSBT and your seed, and gives you back a signed one ready to broadcast.

⌁
Safe on an air-gapped machine. The Sign tab makes no network calls. You can copy this whole file onto a machine that is permanently offline and use only this tab to sign PSBTs that you carry in by USB or QR. The seed never leaves the page and is wiped from memory the moment you close the tab.

## Load PSBT

Paste the base64 PSBT produced by the Build tab (or any PSBT-compatible wallet that targets a BIP-84 native segwit account).

#### PSBT in plain language

A PSBT (Partially Signed Bitcoin Transaction, BIP-174) is a standard file format for a transaction that is being put together in steps.

One tool builds the unsigned shape: which coins to spend, who gets paid, how much fee. Another tool, kept offline with the seed, signs it. A third tool broadcasts the signed transaction to the network.

Hardware wallets, Sparrow, Electrum, and this prototype all speak the same PSBT format. You can hand it around as a base64 string, a .psbt file, or a QR code.

You are now on the Sign tab: load a PSBT below, type your seed, and the tool returns it signed and ready to broadcast.

PSBT (base64)

## Unlock and sign

Type your seed phrase below. It stays in this tab, never leaves the page, and is wiped from memory when you press Forget seed or close the tab.

Seed phrase (12 or 24 words) BIP-39 passphrase (optional, often called the "25th word")
Case sensitive. Same words + different passphrase = different wallet. Most wallets do NOT use one. If you are not sure, leave this empty.

### Lookup endpoints

Block explorers used for the optional online balance and UTXO lookup on the Build tab. Click any name to expand and edit. Toggle the checkbox to enable or skip an endpoint. Add your own Esplora-compatible node at the bottom. Settings live in your browser only.

### Look up balances online?

This is the only step in the Build tab that goes online. The tool will query the block explorers in your settings for the addresses on this page, one at a time, and read back their balance and UTXO list.

The xpub itself never leaves the page. Only individual addresses are sent. The explorers will see the IP that made the request and the addresses you queried. To hide your IP, switch to Tor in the topbar (the page must be loaded in Tor Browser).

Currently selected: Mempool.space (clearnet). Once you confirm, the consent is remembered for the rest of this tab session. Closing the tab resets it.