https://github.com/Bitcoin-II/BitcoinII-Core
BitcoinII is a BitcoinII full-node implementation derived from BitcoinII Core, with a focus on database performance, storage efficiency, node configurability, and selected forward-looking performance improvements.
BitcoinII v31.1. is based on Bitcoin Core v31.1 and remains compatible with the BitcoinII network and BitcoinII consensus rules.
This initial BitcoinII release is provided as source code. Pre-built release binaries are not currently provided.
BitcoinII connects to the BitcoinII peer-to-peer network to download and fully validate blocks and transactions. It also includes the BitcoinII wallet, RPC interface, command-line utilities, and graphical user interface.
BitcoinII is not a separate cryptocurrency and does not define a separate blockchain. It is an alternative BitcoinII node implementation built from the BitcoinII Core codebase.
The primary changes in BitcoinII v31.1.1 include:
- LevelDB database and block-storage architecture aligned with Bitcoin Core v31.1.
- Parallel block-input prevout fetching during block validation, backported from post-v31.1 Bitcoin Core development.
- Consensus-enforced restrictions on arbitrary blockchain data storage.
- BitcoinII-specific branding, configuration naming, network parameters, and application integration.
Further technical information is available in the doc folder.
The following documents describe significant BitcoinII-specific behavior:
Users building BitcoinII from source are encouraged to use the BitcoinII Depends system for reproducible dependency builds.
See the platform-specific build documentation in the doc folder and the depends documentation for additional information.
The primary BitcoinII configuration file is:
bitcoinII.conf
BitcoinII retains the familiar Bitcoin Core configuration model and command-line option format while adding BitcoinII-specific functionality.
The main branch contains the current BitcoinII development and release
history.
Official source release points are identified with version tags such as:
v31.1.1
BitcoinII is derived from Bitcoin Core and continues to incorporate relevant upstream Bitcoin Core development while maintaining the BitcoinII-specific storage, database, performance, policy, and application changes.
The contribution workflow is described in CONTRIBUTING.md, and developer information can be found in doc/developer-notes.md.
BitcoinII inherits Bitcoin Core's extensive unit, functional, fuzz, and integration testing infrastructure and adds or modifies tests where required for BitcoinII-specific functionality.
Unit tests can be compiled and executed with CTest when tests were enabled during build configuration:
ctest
Further information about unit tests is available in src/test/README.md.
Functional and integration tests are located under test/ and can be run using the functional test runner from the configured build tree.
BitcoinII modifies security-critical Bitcoin software. Changes should be reviewed and tested carefully, particularly changes affecting validation, database handling, transaction policy, block storage, or wallet behavior.
BitcoinII is derived from the Bitcoin Core project:
Bitcoin Core source code is available at:
https://github.com/bitcoin/bitcoin
BitcoinII retains substantial Bitcoin Core code, documentation, testing infrastructure, and copyright attribution.
Large portions of BitcoinII is released under the terms of the MIT license, as inhereted from upstream Bitcoin Core.
See COPYING for the full license text or:
https://opensource.org/license/MIT
Exception: Original source code and implementation material comprising the ShockWave Difficulty Adjustment Algorithm is not distributed under the MIT license.
Portions of the ShockWave implementation derived from Bitcoin Core, Dash/Darkcoin, or other pre-existing MIT-licensed software remain subject to their respective MIT license terms. The restrictions below apply only to original ShockWave material for which KvantaMechanic & Second Chance Digital, LLC. holds the applicable copyright.
Copyright (c) 2026 KvantaMechanic & Second Chance Digital, LLC All rights reserved.
Except for portions independently subject to the MIT license as described above, the original ShockWave source code and implementation contained in BitcoinII Core are proprietary software.
The ShockWave source is made publicly available solely for:
- security review;
- technical and consensus audit;
- interoperability analysis;
- academic or technical evaluation; and
- testing of the BitcoinII implementation.
Permission is granted to view the ShockWave source code and to make temporary copies strictly as necessary to inspect, compile, execute, and test it for the review and evaluation purposes listed above.
NO LICENSE IS GRANTED to incorporate, deploy, reuse, redistribute, or exploit the proprietary ShockWave implementation, in whole or in substantial part, in another blockchain, cryptocurrency, distributed-ledger system, software product, service, protocol, or other implementation.
Without prior express written permission from KvantaMechanic & Second Chance Digital, LLC. you may not:
- incorporate proprietary ShockWave source code, or any substantial portion of it, into another project;
- copy, adapt, modify, translate, port, or create derivative works from the proprietary ShockWave implementation except as strictly necessary for permitted review and testing;
- redistribute, republish, sublicense, sell, license, or commercially exploit the proprietary ShockWave implementation;
- deploy the proprietary ShockWave implementation, or a derivative of it, on another blockchain, cryptocurrency, distributed-ledger network, software product, service, or protocol;
- use the proprietary ShockWave implementation as the basis for another production difficulty-adjustment implementation; or
- remove, obscure, or alter this copyright or license notice.
The limited permissions granted for review, audit, compilation, execution, and testing do not constitute an open-source license and grant no rights except those expressly stated.
Nothing in this notice restricts rights independently granted under the MIT license with respect to Bitcoin Core, Dash/Darkcoin, or other pre-existing MIT-licensed code. The proprietary restrictions above apply only to original ShockWave material for which KvantaMechanic & Second Chance Digital, LLC. holds the applicable copyright.
Any use of proprietary ShockWave material outside the expressly permitted review and evaluation purposes requires prior express written authorization from KvantaMechanic & Second Chance Digital, LLC.
THE PROPRIETARY SHOCKWAVE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND NONINFRINGEMENT. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES, OR OTHER LIABILITY ARISING FROM, OUT OF, OR IN CONNECTION WITH THE PROPRIETARY SHOCKWAVE SOFTWARE OR ITS USE.
The official BitcoinII source repository is:
https://github.com/Bitcoin-II/BitcoinII-Core
Issues and source-development reports may be submitted through: