Kusama is a live blockchain network built from the same code as Polkadot, with faster governance and lower costs to launch a chain. This guide explains how the Kusama blockchain relates to Polkadot, what teams build on it, how chains buy blockspace through coretime, and which risks to plan for.
Gavin Wood and the Polkadot founders launched Kusama in 2019, and it is not a testnet. Its token, KSM, trades at a market price, its validators earn and risk real stake, and failures lose real money. The official Kusama motto is "Expect chaos". The Polkadot community calls Kusama a canary network: new features go live there first, so problems appear before they reach Polkadot.
Kusama vs Polkadot
| Aspect | Kusama | Polkadot |
|---|---|---|
| Code base | Polkadot SDK, same relay chain design | Polkadot SDK |
| Governance speed | Shorter voting and enactment periods. The Polkadot wiki says governance on Kusama runs up to four times faster. | Longer periods and a more cautious pace |
| Block time and throughput | Same as Polkadot | Same as Kusama |
| Upgrades | Usually arrive first | Usually arrive after testing on Kusama |
| Cost to run a chain | Lower deposits and coretime prices | Higher |
| Economic security | Less total stake | More total stake |
| Typical users | Experimental projects, early-stage teams, test deployments with real value | Production systems that need stability |
The guide to Polkadot development covers the shared architecture in more detail.
What you can build on the Kusama blockchain
A parachain, which is your own chain
A parachain team writes a runtime in Rust with FRAME, the runtime framework of the Polkadot SDK. The runtime combines modules called pallets for balances, assets, governance and the team's own logic. Collators run by the team produce the chain's blocks, and the Kusama relay chain validators check those blocks and give them shared security and finality.
A parachain makes sense when a project needs one of these things:
- a custom fee model,
- native features that would be hard to write as smart contracts,
- its own governance.
Smart contracts and applications
A team that does not need its own chain can deploy contracts to an existing parachain that supports them, including EVM-compatible parachains. A team can also build an app on the system chains. Asset Hub is the system chain for issuing assets, and in late 2025 it also took over balances, staking and governance from the relay chain. Polkadot's documentation describes support for Solidity contracts on the Hub. An app needs far less operations work than a chain. The guide to Polkadot dApp development covers this route, and the same steps apply on Kusama.
Cross-chain features
Chains in the ecosystem send messages and assets to each other with XCM (Cross-Consensus Messaging). An XCM flow must handle fees and failures on the destination chain, and this design work is one of the hardest parts of any multi-chain build.
Coretime: how a Kusama chain gets blockspace
Kusama first gave parachain slots to the winners of auctions, in which teams locked large amounts of KSM, often raised from their communities through crowdloans. Agile Coretime replaced the auctions, starting on Kusama in 2024.
Under Agile Coretime, a chain buys blockspace, called coretime, on a system chain called the Coretime chain. A chain can buy coretime in two ways:
- Bulk coretime covers a fixed period, currently 28 days per sale region.
- On-demand coretime pays for single blocks when the chain needs them.
Coretime needs far less capital up front than an auction slot, and a chain that produces blocks only now and then can run on on-demand coretime. Check current prices and rules in the official Polkadot documentation, which also covers Kusama.
How to build a Kusama parachain
- Confirm that you need a chain. If a smart contract on an existing parachain would work, use one, because a chain needs operations work for as long as it runs.
- Start from a template. Use the official parachain template and add or remove pallets.
- Write and benchmark custom pallets. Every extrinsic, which is a call into the runtime, needs a weight measured by benchmarks, which sets the fee, and an extrinsic without a benchmark lets attackers fill blocks cheaply.
- Test locally with a relay chain. Zombienet starts a local network, and Chopsticks copies the live chain state for tests.
- Run on the Paseo testnet, the community testnet that most teams use before Kusama.
- Buy coretime, register the chain and start collators. Spread collators across several operators and regions.
- Plan runtime upgrades. The Polkadot SDK upgrades a chain without a fork, but each upgrade still needs storage migrations tested against real state.
Skills and cost drivers
Parachain work needs Rust developers who know FRAME, runtime storage, weights and XCM. Fewer developers have these skills than know Solidity, so Rust parachain developers cost more to hire.
For a parachain with modest custom logic, three Rust engineers and one DevOps engineer usually need three to six months to reach a stable Kusama launch. After launch, the chain still needs collator operations, security reviews and participation in governance. A smart contract app on an existing parachain costs about as much as a normal dApp project. The guide to Polkadot wallet development covers wallet integration.
Risks to plan for on Kusama
- Fast governance. Network changes can pass quickly, so monitor the referenda that affect your chain.
- Small liquidity and user base. Kusama has less liquidity and fewer users than Polkadot or the large EVM chains, and a live chain does not bring users by itself.
- Project turnover. Several projects that won Kusama parachain auctions later shut down or moved, so plan how the chain will pay for itself after launch.
- Cross-chain errors. XCM bugs and wrong asset registrations can lock funds.
Frequently asked questions
What is Kusama?
Kusama is a public blockchain network that runs the same code as Polkadot, with KSM as its token. Kusama gets new features first and has faster governance, so teams use it to test and run experimental chains with real value at stake.
Should I launch on Kusama before Polkadot?
Many teams launch on Kusama first to test with real value at stake, but Polkadot does not require a Kusama launch. Some teams run on both networks permanently and use Kusama for faster experiments.
Do I need KSM to build on Kusama?
Yes. KSM pays for transaction fees, coretime and deposits, in amounts that depend on current prices.
Can I write Kusama smart contracts in Solidity?
Yes, on parachains or system chains that run an EVM-compatible environment, while native runtime logic is written in Rust.