Important Instructions

1) Go to Settings tab.
2) Select your network.Support is available for Bitcoin, Bitcoin Cash, Bitcoin Gold
3) After selecting your network, hit the Submit button to apply the settings for the site.
4a) Select the Time Lock tab to create a time lock P2SH Address (HODL Address).
4b) Select the TX tab to build a transaction using a script.
5) You can verify transactions under the Verify tab.
6) Once a transaction is verified, you can sign it under the Sign tab.
7) Use advanced options with Bitcoin Cash for offline signing. You can download a file of the originating address, which is required for the signing procedure.
8) Once a transaction is signed, you can broadcast it under the Broadcast tab.

New Address create a new address

Any keys used you will need to manually store safely as they will be needed later to redeem the bitcoins.

Address Options

You can use the advanced options below to generate different kind of keys and addresses.

Create Time Locked Address for coins that can be released only after a certain date

Use OP_CHECKLOCKTIMEVERIFY (OP_HODL) to create a time locked address where the funds are unspendable until a set date and time has passed.

Enter the public key that will be able to unlock the funds after the a certain date.

Enter the or required to release the coins:

New HD Address making bip32 even easier

Use the form below to generate a master hierarchical deterministic address.

Address Options

You can use the advanced options below to generate different kinds of master addresses.

Transaction Create a new transaction

Use this page to create a raw transaction

Address, WIF key or Multisig Redeem Script:

Advanced Options


Enter the address and amount you wish to make a payment to.

Enter the details of inputs you wish to spend.

Verify transactions and other scripts

Enter the raw transaction, redeem script, pubkey, hd address or wif key to convert it into a readable format that can be verified manually.

Sign Transaction once a transaction has been verified

Once you have verified a transaction you can sign and then broadcast it into the network.

Advanced Options

Broadcast Transaction into the bitcoin network

Enter your hex encoded bitcoin transaction

Create a Double-spending Transaction

  • Unsigned double-spending transaction will generated at server side and returned back
  • Private Key will be never sent out from your computer, new transaction will be signed in your browser! (Open Source code)
  • You need to specify Private Key of any your Address from the previous still unconfirmed transaction, only this Input will be double-spent
  • If more than one Input with the same Address in the unconfirmed transaction - Input with the highest amount will be double-spent
  • All other Inputs (if any) will be recovered in your wallet when new double-spending transaction confirmed by network
  • You may doublespend each Input (if multiple Inputs) as new transaction or doublespend just any one Input Address
  • New transaction will be broadcasted to the BTC network (repeatedly until confirmed) via our own specially configured nodes (no 258: txn-mempool-conflict error)
  • Double-spending time can not be estimated but usually this is less than 24 hours
  • You will be able to verify New Transaction and check all Outputs and Amounts before Broadcast at Verify Tab (copy-paste it)
  • Bitcoin (BTC) is only supported for double-spending, no Bitcoin Cash, Gold or other bitcoin forks
  • This is not free-of-charge service!
  • Service fee BTC address will be automatically added to newly generated transaction
  • Service fee is 10% of Input Amount, but no less than 0.005 BTC (min) and no more than 0.05 BTC (max)
  • Update: 11.11.2017 - Minimal service fee lowered to 0.0001-0.004 for small transactions only. Do not forget to Verify before broadcast

Please specify your Private Key, previous still unconfirmed transaction TXID, New Output address (previous one is also allowed) and new Network Fee:

(used only within your browser, service will never send it out from your PC)

Submitting button below you request new double-spending transaction, it will not be broadcasted to the Network, you will have a chance to review this before broadcasting!

Development Javascript framework, API and more

This section is currently under development and is subject to change.


Version 1.0 was a modified clone of the project by OutCast3k. is a free and open source project released under the MIT license in 2013. Discussion of the project can be found at is run and funded by the generosity of others in terms of development and hosting.

Version 2.0 merges some modifications from the fork of the project. Now allows for offline signing of Bitcoin Cash and works somewhat with Bitcoin Gold.


There is minimal support. My handle is Pente on Bitcointalk.


These simple settings allow you to select your coin and network. Be sure to click the "Submit" button.


Select which network you'd like to use for key pair generation.


Select the network you wish to broadcast the transaction via

Unspent outputs:

Select the network you wish to retreive your unspent inputs from

This site uses javascript to sign your transactions within your browser, we never receive your private keys. You can even download it and run offline.