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Bitcoin Classic shutting down


Thu 09 Nov, 2017. -- Bitcoin Classic Closing its doors

Bitcoin Classic was started in early 2016 with the clear intention of coming back to the coin that Satoshi indicated as his goal. Now this goal has been reached we will step down.

Release Announcement Bitcoin Classic 1.2.5


April 25, 2017. This release fixes a set of smaller and larger stability issues.

We recommend Bitcoin Classic version1.2.5 for everyone, especially if you already were running a version with thinblocks (xthin).

For more help with installation, and instructions how to download please visit

Download page

Release Announcement Bitcoin Classic 1.2.3


March 22, 2017. Following a string of issues with code that Classic borrowed elsewhere, we finally took responsibility for the adopted code and fixed a lot of issues in that code which directly affect stability and reliability of a node.

Additionally, this feature makes the existing flag -use-thinblocks a proper flag which allows the operator to fully turn it off, making the code of this feature unable to be executed by misbehaving networking nodes.

We recommend Bitcoin Classic version1.2.3 for everyone, especially if you already were running a version with thinblocks (xthin).

For more help with installation, and instructions how to download please visit

Download page

Release Announcement Bitcoin Classic 1.2.1


Thursday, 23 February 2017. Today we release a Bugfix update to Bitcoin Classic, version 1.2.1. Classic 1.2.0 was released 8 weeks ago with the decentralized block size solution and various new features.

Bitcoin Classic 1.2.1 is fully compatible with Bitcoin Core downloaded block chain and wallet.

This release adds a two months' worth fixes from Classic's contributors. The bugfixes are typically small but important and include:

  • Make splashscreen work on hi-DPI displays commit
  • [Qt] Bugfix: ensure tray icon menu is not empty PR
  • [Qt] Update data size in first run GUI commit
  • Fix failing QA test PR
  • Make compile on FreeBSD. See issue
  • Make configure detect old Boost. commit
  • Allow parsing of incomplete (no signature) flextrans transactions. commit
  • Punish peers relatively for oversize blocks commit

For more help with installation, and instructions how to download please visit

Download page

Release Classic 1.2.0

January 5, 2017. Today Bitcoin Classic announces the release of version 1.2 of the stable full node client.

This release marks a change in strategy for Bitcoin Classic, moving from the very conservative block size proposal based on compromise to one where Classic truly innovates and provides a long term solution for the market to choose and leave behind the restrictions of the old.

The most visible change in this version is the decentralised block size solution where node operators decide on the maximum size. This idea is already getting major acceptance in the market.

Bitcoin Classic is focused on providing users a way to get onto the Bitcoin network using a high quality validating node for a large set of use cases. Classic presents top notch quality processes in this release, to help anyone running Bitcoin.

We include in this release various projects with the beta label. People who want to use the Classic node as an on-ramp to Bitcoin will find them interesting. These projects will need to be enabled in the config by those that want to test them.

More background information on this release and Classic can be seen in this video:

Bitcoin Classic ships several exciting technologies in this release:

  • Decentralise block maximum size This is the answer to the block size debate, operators can decide themselves what size limit to enforce.
  • Flexible Transactions A beta version that solves problems like the malleability issue using an upgrade to the transaction format. This is meant for further testing on testnet-ft.
  • Admin Server Use your full node as a gateway to Bitcoin for high speed access and remote monitoring purposes. Feature incomplete and thus marked beta.
  • Network Manager A new low-level component that is currently used by the Admin Server. It is build for high speed communication with many hosts at the same time.
  • Linux improved packaging standards. For Linux we package Classic for the distro families Ubuntu and ArchLinux. These packages now allow the most convenient way of running a node with no configuration needed and pre-configured systemd and cookie-based bitcoin-cli remote management integration.
  • xthin block transfer technology This technology was adopted from another client as a way to make sending blocks and immensely faster and more bandwidth friendly.

For more help with installation, please visit

Flexible Transactions (update)

This is episode 4 of toms crypto channel. In this episode Tom goes over the Flexible Transactions proposal for Bitcoin, a protocol upgrade that solves a list of issues.
This video can be seen as an introduction to the technology as the actual research and development is feature complete where we proceed to the stabilising phase.

Upgrading Bitcoin's Protocol

What things are relevant as to decide what the best way is to add features and what it means to upgrade the Bitcoin protocol?

In episode 3 Tom talks about how upgrades of Bitcoin can be done, Tom looks back at past decisions that have left Bitcoin harder to maintain and harder to extend for many years to come. He looks forward as well by comparing various proposals for future extensibility.

Risk of Scaling

What risks are there when we talk about Scaling Bitcoin?

In episode 2 Tom talks about how much room we have for scaling before things break.

Flexible Transactions Introduction

Tom invented a new concept of storing transactions in Bitcoin which he called Flexible Transactions. This video introduces the ideas behind flexible transactions and how they may change Bitcoin for the better and allows Bitcoin to scale to the next billion.

OnChain Scaling Conference

Steady Growth Comes From Steady Innovation

Tom Zander's talk takes a look at bitcoin communication on the network. Tom explains how it works and attempts to find various parts that could become better. He will explain one solution for scaling which he coined Optimistic Mining more in depth. (27 min +Q&A)

Release 1.1.1 and 1.2 (Beta) with Flexible-transactions and Xthin Support

Bitcoin Classic 1.1.1 Release Announcement (released September 19)

The Classic team is happy to announce a bugfix release 1.1.1 This release includes binaries, which can be downloaded from github

Bitcoin Classic 1.1.1 is based on Bitcoin Core version 0.12.1, and is compatible with its blockchain files and wallet. Additionally, this release includes the increase of the block size limit from one megabyte to two megabytes. This bugfix release fixes various issues and we believe this is the best stable version of Classic and we recommend everyone upgrade as soon as possible.

One notable change is that starting at this release Bitcoin Classic will no longer respond to network-alerts. This change means we no longer have to trust certain people that never really had any association with Bitcoin Classic.

Bitcoin Classic Beta Release 1.2 (released September 20)

Bitcoin developer, Tom Zander announced Flexible Transactions and Xthin-blocks support was added to Beta 1.2 today, the first milestone towards the release of Bitcoin Classic 1.2. This beta version is now ready, and can be downloaded from github.

As a new minor release, 1.2 comes with a lot of new features as well as many bug fixes and improvements.

There will be more detail as we get closer to the release.

Flexible Transactions — FlexTrans is a new transaction format that solves all cases of transaction malleability and thus makes Bitcoin ready for future technologies like the Lightning Network. It also cleans up a lot of technical debt and provides a clear road forward for a long list of protocol improvements which will be possible, equally clean and technical-debt free.

For instance FlexTrans allows us to remove signatures from a block after it has been validated, which in practice means about 75% size reduction. Additionally this technology completely replaces any need for segregated witness. Flexible Transactions is a new technology and would benefit from more usage and testing. This release does not allow Flexible Transactions on main-net.


Xthin-blocks - This release includes support for the extra-thin blocks technology which solves the problem of block propagation causing delays because it only sends a small fraction of the data when a block is found and cleverly rebuilds it from the mempool of its own node.