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NOTE: This repository has been moved. Work is continuing under the @statechannels organization as part of project to unify state channels initiatives.


Simple off-chain applications framework for Ethereum.

circleci license

Counterfactual is a simple off-chain framework for building state channel applications on top of the Ethereum blockchain. It aims to make it simpler to build permissionless applications that have instant finality with zero-fee transactions.

You can learn more about what state channels are by reading our whitepaper or a less technical written description. Further, if you want to dive into the specifications of the Counterfactual protocol you can read them here.


Solidity Packages

Package Version Description
@counterfactual/cf-funding-protocol-contracts npm Contracts implementation of the Counterfactual funding protocol
@counterfactual/cf-adjudicator-contracts npm Contracts implementation of an AppInstance Adjudicator

Typescript/Javascript Packages

Counterfactual-specific packages

Package Version Description
@counterfactual/node npm The core state channels client that a user runs
@counterfactual/cf.js npm A JS API for interacting with off-chain apps
@counterfactual/node-provider npm Wrapper around API calls to a Node


Package Version Description
@counterfactual/types npm Shared type declarations
@counterfactual/typescript-typings npm Shims for external library typings


Ethereum Networks

The Playground currently only supports the Kovan network.

Installing dependencies

Make sure you have Yarn v1.19.0 installed. For easy management of specific Yarn versions, we recommend using Yarn Version Manager (YVM).

To install the dependencies:


Building packages

It is recommended (optional) that you installed solc compiler binary on your machine (installation guide) and specify the following in your .env under cf-funding-protocol-contracts and apps


To build all packages:

yarn build


To clean all packages:

yarn clean


To lint all packages:

yarn lint

To also apply automatic fixes:

yarn lint:fix


To run all tests:

yarn test

To run E2E tests:

  • If you're using E2E tests for the first time or have done recent changes to the code, run:
yarn test:e2e:setup
  • If you're re-running tests or writing new scenarios, run:
NODE_EXTENDED_PRIVATE_KEY="..." yarn test:e2e

See the "Funding the Hub Account for Playground Testing" section on the Simple Hub Server package for more information about NODE_EXTENDED_PRIVATE_KEY.


We generate patches using the patch-package tool with a workaround described in this issue for yarn workspaces.