The IoP blockchain client reimplemented.
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Latest commit fb9625f Sep 27, 2018

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The IoP Blockchain client version 6.2.3 is now available


Fixed bug that causes nodes to crash if a new block contains duplicate inputs (recently discovered in bitcoin core) Fixed segregation fault on running iop-qt with startup arguments that cause the program to exit before the Qt backend is initialized. Fixed strange behavior of the IOP buy dialog. Input field will now change color if input is out of range instead of rejecting input.

Known Issues

Toolbar icons still render imperfectly Scaling on Linux and Windows is still broken. To work around it, start the program with QT_SCALE_FACTOR=2 iop-qt or equivalently. We received feedback about some possible UI improvements. Stay tuned!


We are proud to announce a complete redesign of the IoP Core wallet. You can now buy IOP directly from inside the wallet software thanks to our collaboration with Indacoin.


This major release is meant to replace the old version of the IoP Blockchain client. While the consensus remains fully compatible, the structure of the data directory does not. Please read the release notes very carefully if you update from version 5.0.1 or below.

What is IoP?

IoP is an experimental digital currency that enables instant payments to anyone, anywhere in the world. IoP uses peer-to-peer technology to operate with no central authority: managing transactions and issuing money are carried out collectively by the network. IoP Core is the name of open source software which enables the use of this currency.


IoP Core is released under the terms of the MIT license. See COPYING for more information or see

Development Process

The master branch is regularly built and tested, but is not guaranteed to be completely stable. Tags are created regularly to indicate new official, stable release versions of IoP Core.

The contribution workflow is described in

The Discord channel should be used to discuss complicated or controversial changes before working on a patch set.


Testing and code review is the bottleneck for development; we get more pull requests than we can review and test on short notice. Please be patient and help out by testing other people's pull requests, and remember this is a security-critical project where any mistake might cost people lots of money.

Automated Testing

Developers are strongly encouraged to write unit tests for new code, and to submit new unit tests for old code. Unit tests can be compiled and run (assuming they weren't disabled in configure) with: make check. Further details on running and extending unit tests can be found in /src/test/

There are also regression and integration tests, written in Python, that are run automatically on the build server. These tests can be run (if the test dependencies are installed) with: test/functional/

The Travis CI system makes sure that every pull request is built for Windows, Linux, and OS X, and that unit/sanity tests are run automatically.

Manual Quality Assurance (QA) Testing

Changes should be tested by somebody other than the developer who wrote the code. This is especially important for large or high-risk changes. It is useful to add a test plan to the pull request description if testing the changes is not straightforward.