Gerbera

Gerbera is a Bitcoin offline transaction builder used to generate a raw hex Bitcoin transaction.

What's Supported

• Send to:
  • P2PKH
    (1-Addresses. Regular and compressed)
  • P2SH
    (3-Addresses, including SegWit)
• Spend from:
  • P2PKH
    -produced outputs (1-Addresses)
  • P2SH-P2WPKH
    segwit outputs (3-Addresses)
• Signature types
  • SIGHASH_ALL
• Multiple inputs from different addresses (signed with different keys) in one transaction
• Multiple outputs in one transaction
• Unspendable outputs with
  OP_RETURN
  (To put arbitrary data into blockchain)
• Networks
  • MainNet
  • TestNet
• Usage
  • As library
  • Command line application

Help

• Where to find unspent outputs to fill transaction inputs
• How to broadcast raw transaction to network
• How to use command line tool

Quick examples

Build multiple-outputs transaction

The following is an example of how to build a transaction with one input and three (2 custom and 1 for change) outputs.

As library

Command line tool

If (all inputs) - (all outputs) - fee gives positive value, it will be send to

Build multiple-inputs transaction

The following is an example of how to build a transaction with three inputs and one output:

As library

In case change address is not explicitly included (like in this example), but change is present, an

Command line tool

Transaction may contain multiple inputs and multiple outputs at the same time.

Put arbitrary data in transaction with OP_RETURN

Arbitrary data may be placed into transaction with Bitcoin built-in unspendable outputs functionality utilizing OP_RETURN.

To create unspendable outputs use:

As library

This will add two additional unspendable outputs to a transactions.

Command line tool

Build transaction for TestNet

As library

To build a TestNet transaction, create a

Command line tool

Note that in TestNet, addresses and WIFs have different prefixes.

Get transaction hex

As library

The built transaction object may be used to get raw transaction hex:

The output is a

Command line tool

Result example:

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

Get transaction field-split representation

As library

The transaction object may be also used to get field-split hex transaction representation that makes reading raw hex easier.

Command line tool

Result example:

Version                  01000000
Input count              01
   Input
      Transaction out    7ee6299e47cc5807c81df5a06806c3c3cf3aa7b0152189d109056c8cdb1282fb
      Tout index         0d000000
      Unlock length      8a
      Unlock             47304402206fb7d70259301222232e8e006cf1d0c6814666e52b5379e04b7cef0d695c4ff202205323e65a65bd74d904d02dfa3d33bfd1d937cd82fadf1a41d9da9d288498163a01410479be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b8
      Sequence           ffffffff
Output count             03
   Output (Custom)
      Satoshi            6842000000000000
      Lock length        19
      Lock               76a914ec7eced2c57ed1292bc4eb9bfd13c9f7603bc33888ac
   Output (Custom)
      Satoshi            204e000000000000
      Lock length        17
      Lock               a914000102030405060708090001020304050607080987
   Output (Change)
      Satoshi            9401000000000000
      Lock length        19
      Lock               76a9144747e8746cddb33b0f7f95a90f89f89fb387cbb688ac
Locktime                 00000000

For SegWit transactions (spending SegWit outputs), result example is:

Version                  01000000
Marker                   00
Flag                     01
Input count              02
   Input (Segwit)
      Transaction out    82cb6eb26722118afac52ba256f8753f44de29637bb874fa5d952ebdf952a8cb
      Tout index         02000000
      Unlock length      17
      Unlock             160014033118abb28063208561dc3ce63bdb32880a78ef
      Sequence           ffffffff
   Input
      Transaction out    84b1959dbc3e7dd49b90b5012922a82022fc5cf2df6d0fe23a2d1ad8d615d3cf
      Tout index         00000000
      Unlock length      8b
      Unlock             483045022100c592992fffde118fe8b37e30ee46b7a6ca276be5486c3022e6e20ad4bec5947b02203772a20074aacf7dd3cd37fc36afeba88d8e114fa1e8191bd9bc9b52a38db26a0141047cab4279ec773172c1eeb65b7292149df9bb2f1fb6c7dcacf043aabb893ad19fa90c4286bbb50b211ce6e272dccd511310041c2843af6059d90df4a186782134
      Sequence           ffffffff
Output count             01
   Output (Custom)
      Satoshi            49cdec0600000000
      Lock length        17
      Lock               a914a9974100aeee974a20cda9a2f545704a0ab54fdc87
Witnesses
   Witness               0247304402206bb7c127506f6c25fead2071744014e6111da6af31092e45a1c8eefb73cebb3a02205c2573d4d35bfa5982af5067bcca90473c5cf83844420ab2954d31503abcec9f0121030d7ca27f28ea0b5b4b57605d9ec3f05a2858667529f65797f1cc4b50e2be149f
   Witness               00
Locktime                 00000000

Get additional transaction information

As library

To get additional transaction info (size in bytes and satoshi/byte fee) call the following method of the

Command line tool

Result example:

Size (bytes):
  292
Fee (satoshi/byte):
  10.274

For SegWit transactions, fee-per-byte is calculated based on vertual size:

Virtual Size (bytes):
  292
Fee (satoshi/byte):
  10.274

How to compile

First clone the project:

Then build a jar:

The jar

How to use

As library

Add the built jar to your project and start from

Command line tool