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This repo is provides core functionality to all clients in a cross-platform typescript library. This can be used to build cli/gui clients, automated scripts, or help build bcp-proxy apps.

Main functionality provided:

  • Solid crypto library with HD support for ed25519 (following SLIP-0010, ledger compatible)
  • Secure private key management, including encrypted local storage for both browser and node
  • Generic, type-safe adaptor to read/write on tendermint rpc server (with http/s and ws/s support)
  • Adaptor to query / create transactions for IOV's testnet of the BNS blockchain
  • Adaptor for key management using IOV's BNS ledger app
  • High level controller for managing multiple user profiles and various key material
  • High level controller for managing read/write connections to multiple blockchains (CoreWriter)
  • Integration with REPL environment for quick prototyping for developers

This is still in pre-alpha state and will evolve quickly as we add support for multiple blockchains, more transactions types, and better extensibility. However, all attempts have been made that the foundational code is quite solid. A security audit and stable release will occur along with the timeline of IOV's mainnet launch, but developers looking for client-side libraries can do initial prototypes with the current state.

We are actively building out multiple clients on top of this library and shaking out usability issues in the API.


The following projects use IOV-Core (add yourself via a PR):

Project Tech stack / JavaScript environments
TokenFinder TypeScript / React / Browsers
iov-faucet TypeScript / NodeJS 10
@iov/ledger-bns TypeScript / NodeJS / Browsers


The compiled code from this package, which is published on npm, should work on any modern (2018) browser, and node 10.13+. The development environment has been tested on node 10.13.

Yarn not Npm Please npm install -g yarn and use yarn install, yarn build, etc. Developers who installed with npm i have reported problems in compiling, so wipe out node_modules and enjoy yarn.

CI Tests:

  • Linux: node 10.13, chrome, (electron manually)
  • OSX: node 10.13, chrome, firefox, safari, (electron manually)
  • Windows: node 10.13, (edge, electron manually)

Getting Started

The best way to learn about code is to use it. You can read some examples in @iov/multichain. And you can use a REPL to interactively try the code.

Once you understand the basics, you can dig in deeper with the API documentation.

API Docs

Documentation is published at

To build the documentation locally, run yarn install && yarn build && yarn docs in this repository. This will generate a ./docs directory in each package that you can browse locally to see API docs on the various packages.


We are more than happy to accept open source contributions. However, please try to work on existing issues or create an issue and get feedback from one of the main contributors before starting on a PR. If you don't know where to start, we try to tag "good first issues" that provide a nice way to get started with the IOV-Core repo.

Development Environment

If you go into a subpackage and try to yarn build or yarn test, chances are it will fail. The reason is that we only check in *.ts files, while we need the compiled *.js files to import other packages. We push these to npm but do not check them into git to avoid commit noise.

To get started, please go to the root directory and run:

yarn install
yarn build
yarn test

Once that passes, you have the code built and can go into any subdirectory, edit code and verify the changes with yarn test on that one package.

Integration Tests

There are a number of integration tests involving communication with tendermint (in @iov/tendermint-rpc) and the BNS blockchain (in @iov/bns) that require a test server to run and are skipped by default. If you are working on those packages, please run those tests. (They require docker to be installed and executable by the current user)



cd packages/iov-tendermint-rpc
yarn test
cd ../..



If you are working on @iov/bns, you can run the tests against a local BNS devnet. See scripts/bnsd/ for instructions on how to start the BNS devnet. Then run the tests as follows:

cd packages/iov-bns
yarn test


If you are working on @iov/lisk, you can run the tests against a local Lisk devnet. See scripts/lisk/ for instructions on how to start the Lisk devnet. Then run the tests as follows:

cd packages/iov-lisk
yarn test

Browser tests

The CI runs all code not only under node, but also in various browsers.

These work almost all of the time, but if you CI test fails in the browser, or if you are just curious to see this work, you can run the browser tests locally with any of the following, in any package you are working on:

yarn test-chrome
yarn test-firefox
yarn test-safari  # osx only
yarn test-edge    # windows only

Developing under Windows 10

Most of the developers working on this project in windows are also using Windows Subsystem for Linux (WSL), which should have maximum compatibility, as CI is linux and osx. However, we do attempt to ensure that this code also compiles on the normal windows shell, if you have set up git, node, yarn etc. correctly. (Note this has only be verified under windows 10, no guarantees for older versions).

Line endings (CRLF vs LF)

All the code in the repo should use LF not the windows-specific CRLF as a line ending. tsc is currently set up to output properly. However, you should also make sure your editor saves with LF line endings rather than CRLF.

A bigger issue is git changing the endings upon commit. Here is a short workaround, adapted from a stackoverflow discussion:

git config --global core.autocrlf false
git config --global core.eol lf

FAQ For Potential Issues

Libusb fails to build, why?

If you are running on linux, you may not have the proper dependencies installed. For Ubuntu, try the following: sudo apt-get install libudev-dev libusb-1.0-0 libusb-1.0-0-dev. These are needed to compile the usb driver.

Sometimes compiling native code with node-pre-gyp causes issues in very recent versions of Node.js. At the moment, Node.js 10 and 11 should work.

Docker fails to run a test server

If you're using OSX and Docker Desktop for Mac and you get an error like the following, you'll need to add your $TMPDIR path to the list of shared paths:

docker: Error response from daemon: Mounts denied:
The path /path/to/tmpdir is not shared from OS X and is not known to Docker.
You can configure shared paths from Docker -> Preferences... -> File Sharing.
See for more info.

In a terminal, run this command to find out your $TMPDIR:

echo $TMPDIR

Then add it to the list of shared paths in Docker -> Preferences ... -> File Sharing. Apply and restart, and try to start the test server again.

My PR works but the CI rejects it

Make sure you at least ran yarn test in all the directories where you modified code. The CI will reject any PR if type definitions change after compiling the code to ensure it was build and committed prior to pushing.


This repository is licensed under the Apache License 2.0 (see NOTICE and LICENSE).


Client library for secure key management and multi-blockchain communication





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