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Implementation of a node in Rust.


In 2017 we split our implementation of "Polkadot" from its platform-level component "Substrate". When we split them, we split the Polkadot code off into another repo (this repo), leaving the Substrate repo to be what used to be Polkadot, along with its branches and releases.

We are actively building both Substrate and Polkadot, but things will be a little odd for a while. If you see "substrate" and are wondering why you need it for Polkadot, now you know.

To play on the ("Alexander") testnet, you’ll want the PoC-4 code which is in this Polkadot repo. Note that PoC-3 uses the Alexander testnet, but will not be able to sync to the latest block.

  • Polkadot PoC-4 "Alexander" is in this Polkadotrepo branch v0.4

  • Polkadot PoC-3 "Alexander" is in this Polkadotrepo branch v0.3

  • Polkadot PoC-2 "Krumme Lanke" is in the Substrate repo branch v0.2

2. To play

2.1. Install Rust

If you’d like to play with Polkadot, you’ll need to install a client like this one. First, get Rust (1.32.0 or later) and the support software if you don’t already have it:

curl -sSf | sh
sudo apt install make clang pkg-config libssl-dev

If you already have Rust installed, make sure you’re using the latest version by running:

rustup update

2.2. Install PoC-4 on "Alexander" Testnet

Build Polkadot PoC-4 by cloning this repository and running the following commands from the root directory of the repo:

git checkout v0.4
cargo build --release

If you were previously running PoC-3 on this testnet, you may need to purge your chain data first:

./target/release/polkadot purge-chain

Finally, connect to the global "Alexander" testnet by default by running:


2.3. Install PoC-3 "Alexander" Testnet

Note: Connecting to the current Alexander testnet with this version will not allow synchronization.

Install Polkadot PoC-3 and have a polkadot binary installed to your PATH with:

cargo install --git --branch v0.3 polkadot

Connect to the global "Alexander" testnet by default by running:


2.4. Install PoC-2 "Krumme Lanke" Testnet

Install Polkadot PoC-2 and have a polkadot binary installed to your PATH with:

cargo install --git --branch v0.2 polkadot

Connect to the global "Krumme Lanke" testnet by default by running:


2.5. Install a custom Testnet version

You can run the following to get the very latest version of Polkadot, but these instructions will not work in that case.

cargo install --git polkadot

If you want a specific version of Polkadot, say 0.2.5, you may run

cargo install --git --tag v0.2.5 polkadot

2.6. Obtaining DOTs

If you want to do anything on it (not that there’s much to do), then you’ll need to get an account and some Alexander or Krumme Lanke DOTs. Ask in the Polkadot watercooler ( ) or get some from the Polkadot Testnet Faucet ( ).

2.7. Development

You can run a simple single-node development "network" on your machine by running in a terminal:

polkadot --dev

You can muck around by cloning and building the and or just heading to and choose "Alexander (hosted by Parity)" from the Settings menu.

3. Building

3.1. Hacking on Polkadot

If you’d actually like hack on Polkadot, you can just grab the source code and build it. Ensure you have Rust and the support software installed:

curl -sSf | sh
sudo apt install cmake pkg-config libssl-dev git clang

Then, grab the Polkadot source code:

git clone
cd polkadot

Then build the code:

./scripts/   # Install WebAssembly. Update Rust
./scripts/  # Builds the WebAssembly binaries
cargo build # Builds all native code

You can run the tests if you like:

cargo test --all

You can start a development chain with:

cargo run -- --dev

Detailed logs may be shown by running the node with the following environment variables set:

RUST_LOG=debug RUST_BACKTRACE=1 cargo run —- --dev

3.2. Local Two-node Testnet

If you want to see the multi-node consensus algorithm in action locally, then you can create a local testnet. You’ll need two terminals open. In one, run:

polkadot --chain=local --validator --key Alice -d /tmp/alice

And in the other, run:

polkadot --chain=local --validator --key Bob -d /tmp/bob --port 30334 --bootnodes '/ip4/'

Ensure you replace ALICE_BOOTNODE_ID_HERE with the node ID from the output of the first terminal.

3.3. Using Docker

3.4. Shell Completion

3.5. Polkadot Networks

4. Contributing

4.1. Contributing Guidelines

4.2. Contributor Code of Conduct

5. License

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