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Version: 4.x

Install cargo-contract

cargo-contract is a command-line (CLI) tool which helps you set up and manage WebAssembly smart contracts written with ink!. You can find it here on GitHub and here on

The tool has a number of handy capabilities:

$ cargo contract       
Utilities to develop Wasm smart contracts

Usage: cargo contract <COMMAND>

new Setup and create a new smart contract project
build Compiles the contract, generates metadata, bundles both together in a `<name>.contract` file
check Check that the code builds as Wasm; does not output any `<name>.contract` artifact to the `target/` directory
test Test the smart contract off-chain
upload Upload contract code
instantiate Instantiate a contract
call Call a contract
decode Decodes a contracts input or output data (supplied in hex-encoding)
help Print this message or the help of the given subcommand(s)

-h, --help Print help information
-V, --version Print version information


Please see the installation instructions in the cargo-contract repository here.

You can then use cargo contract --help to start exploring the commands made available to you.


In order to initialize a new ink! project you can use:

cargo contract new flipper

This will create a folder flipper in your work directory. The folder contains a scaffold Cargo.toml and a, which both contain the necessary building blocks for using ink!.

The contains our hello world contract ‒ the Flipper, which we explain in the next section.

In order to build the contract just execute these commands in the flipper folder:

cargo contract build

As a result you'll get the file target/flipper.contract. It's a JSON which bundles the contract's metadata and its Wasm blob. This file needs to be used when deploying the contract. You additionally get the individual target/flipper.wasm and target/flipper.json in the folder as well.