Spawn is a free, open source tool that generates a new Cosmos SDK blockchain, built for Web3 developers and blockchain teams who want a working starting point instead of assembling every piece by hand. It is written in Go, and Spawn for Windows is offered as a Windows build or installer, with builds for macOS, Linux and Docker also available.
The project covers more than the chain skeleton. Testing, GitHub integrations and quick instant testnets are part of the package, so a team can move from an idea to a running network without first building its own pipeline. The latest release is v0.50.16, and the last code update landed on July 30, 2025, which keeps the project current as of this writing.
What Is a Cosmos SDK Blockchain?
The Cosmos SDK is a framework for building application-specific blockchains, written in Go. Instead of deploying on one shared smart contract platform, a team builds its own chain with the features it needs, such as token logic, governance and staking modules, and then connects it to the wider ecosystem.
Each chain runs its own validators and consensus, and it can communicate with other chains through the Inter-Blockchain Communication protocol, usually called IBC. This design gives a project control over its rules and upgrades, but it also means the team is responsible for keeping its own network running.
Spawn helps with the starting point. It produces a project that already follows Cosmos SDK conventions, so the work shifts from wiring infrastructure to designing what the chain actually does.
Developers new to the framework should expect a learning curve. Understanding modules, transactions and how validators agree on state is worth the time before moving toward production.
Who Is Spawn For?
Spawn fits developers who want to experiment with a Cosmos SDK chain without spending their first week on setup. A few typical situations show where it earns its place.
A product team might be weighing whether an app-specific chain makes sense for its service. Generating a working prototype lets the team test the idea, observe how modules behave and show stakeholders something concrete before committing a larger budget.
A solo developer learning Go and the Cosmos stack can read a generated project, change one module and watch the effect in a local testnet. That feedback loop is often more useful than reading documentation alone.
Infrastructure engineers can use the built-in workflows as a template for their own repositories. The GitHub Actions setup shows one way to run checks automatically on every change.
Spawn is less suited to teams that need a fully custom architecture from the first line of code, or to developers who work only with Ethereum-style contracts.
Testnets, Devnets and Why Iteration Matters
Blockchain development relies on several kinds of test environments, and the differences matter when you use a tool like Spawn. A testnet mimics a production chain but uses tokens with no real value. A devnet is usually a smaller, developer-controlled environment for quick experiments.
Running a local instance lets you start and stop the chain as often as you need. You can break things, reset state and try a different module set without affecting anyone else. A local Cosmos Hub devnet adds a second layer, showing how a new chain behaves when it interacts with a network many developers already know.
Iteration is the main practical benefit. Each cycle of change, test and observe gives feedback on configuration, module interactions and integration points. Keeping cycles short helps teams catch mistakes while they are still cheap to fix.
Document each test run. Recording the module set, the chain version and the results makes it easier to reproduce a bug later and to explain design decisions to teammates.
Key features
Tailor-Fit Module Selection
Familiar Cosmos Tooling
Built-In Integrations and Tests
Rapid Iteration Against Live Networks
Supported coins
The project's documentation points to the Cosmos network and its native token, ATOM, as the reference ecosystem. Spawn targets Cosmos SDK chains, so it is most relevant to developers building within the Cosmos ecosystem rather than on Ethereum-style networks.
How to install Spawn on Windows
- 1
Check Your Prerequisites
Before you begin, make sure Go 1.22 or newer is installed, along with Docker and git. The setup instructions rely on these tools, and checking their versions first prevents most early errors when you generate your first chain.
- 2
Download the Windows Build
Download only from the official website or the project's GitHub Releases page at github.com/rollchains/spawn. Choose the Windows build or installer that matches the release you want, and avoid mirror sites or links shared in chat.
- 3
Verify the File
If the release page publishes a SHA-256 checksum or a signature, compare it with your downloaded file before running anything. A mismatch means the file should not be installed, and you should download it again from the official source.
- 4
Install the Program
Run the installer, or extract the build into a folder you have added to your PATH. Open a new terminal window afterward so the updated path takes effect, and confirm the program starts from the command line.
-
Follow the Windows Setup Guide
The documentation includes setup guides for macOS, Windows and Ubuntu. Follow the Windows guide for the exact commands, since they can change between releases and the guide reflects the most recent setup steps.
System requirements
- Windows, with the Windows build or installer available from the project
- Go 1.22 or newer, needed to build the chains Spawn generates
- Docker, as referenced in the setup instructions
- git, used for version control and GitHub integrations
How to use Spawn
Spawn works best when you plan the chain before generating it. Decide what the network needs to do, then move through the workflow below and check each result before going to the next step.
- Define the purpose of your chain and write down which features it must support.
- Select the modules you need, leaving out anything the design does not require.
- Generate the project, which includes the GitHub Actions workflows and end-to-end tests.
- Run the included tests locally and fix any failures before changing more code.
- Start a local testnet and confirm that blocks are produced as expected.
- Test the new chain against the local Cosmos Hub devnet to observe how it interacts with an established network.
- Push the project to GitHub so the Actions pipeline runs on every change and keeps your team informed.
Pros & cons
- Free and open source, with the source code published on GitHub
- Generates Cosmos SDK projects that follow native Cosmos conventions
- Includes GitHub Actions and end-to-end testing from the start
- Lets you choose modules instead of working from a fixed template
- Supports quick iteration against the local Cosmos Hub devnet
- Available as a Windows build or installer
- Focused on Cosmos SDK chains, so it is not a general tool for other blockchain stacks
- Requires Go, Docker and git in your environment, which adds setup work for newcomers
- Still requires solid knowledge of the Cosmos SDK to customize the generated chain
- The most recent code update is from July 2025, so check activity before relying on it for a long project
Is Spawn safe?
Spawn is open source, so you can review its code on GitHub before running it. Download only from the official website or the GitHub Releases page, never from mirror sites or links shared in chat. When a release publishes a SHA-256 checksum or signature, compare it with your downloaded file before running the installer.
Never enter a seed phrase on third-party websites, even ones that claim to be affiliated with the project. Keys generated during testing should stay on test networks, and you should not reuse them on any network that holds real value.
The last code update came in July 2025, so confirm the current status and the latest version on the official website before starting a long-term project.
- Official source only. Download from github.com/rollchains/spawn. Ignore ads and lookalike domains.
- Check the SHA-256. Compare the installer hash with the value the developer publishes before running it.
- Never share your seed phrase. No developer, support agent or website — including CryptApps — will ever ask for it.
Alternatives
Spawn sits at a specific point in the Cosmos toolchain. Cosmos SDK is the framework you write against directly, so it offers full control but leaves you to assemble the project yourself. Spawn starts from a generated project and adds testing and CI from the beginning. Local Interchain focuses on spinning up a local IBC environment, which suits teams testing connections between chains rather than generating a new chain. Ethermint and Native Evmos bring Ethereum-compatible execution to Cosmos, a different goal from building a standard Cosmos SDK chain. Choose Spawn when you want a new chain with ready-made tests and workflows, and choose a framework or environment tool when you already have a codebase or need a narrower function.
Specifications
- Price
- Free
- Type
- Open source
- License
- —
- Latest version
- v0.50.16
- Last update
- 30 Jul 2025
- Windows support
- Yes (Windows build or installer)
- Source code
- github.com/rollchains/spawn
Frequently asked questions
Yes, Spawn is free and open source. The source code is published on GitHub at github.com/rollchains/spawn, so developers can read how the generator works and contribute to it. There is no paid tier, and you can use it for experiments, learning projects and early prototypes without buying a license.
Yes. Spawn is available as a Windows build or installer, and the project also supports macOS, Linux and Docker. Before generating a chain on Windows, install Go 1.22 or newer, Docker and git, then follow the Windows setup guide in the documentation for the exact steps.
Go 1.22 or newer, Docker and git are the main prerequisites. Go is needed to build the chains Spawn generates, Docker supports the environment, and git handles version control and GitHub integrations. Check the setup guide for your operating system, since commands and dependency versions can change between releases.
A Cosmos SDK blockchain is an application-specific chain built with the Cosmos SDK, a Go framework. Each chain runs its own network and defines its own modules for features such as tokens and governance. Teams choose this model when they want control over their rules and upgrades instead of deploying on a shared platform.
No. Spawn generates Cosmos SDK blockchains, not Solidity contracts or Ethereum-style applications. If your work centers on Solidity, a tool such as Remix Desktop is a better fit for writing and testing contracts. Spawn suits developers working within the Cosmos ecosystem and its native toolchain.
The latest release is v0.50.16, and the last code update was made on July 30, 2025. That is recent enough to make the project a reasonable choice for current work. Check the GitHub repository for recent activity before depending on it for a long-term project.
A testnet mirrors a production chain's behavior but uses tokens without real value. A devnet is usually a smaller environment for developers to run quick experiments, often under their own control. Testing against a local Cosmos Hub devnet makes early experiments fast and private.
Yes. GitHub Actions workflows and end-to-end testing are configured from the start of a generated project. This gives you automated checks on each change without writing the pipeline yourself. You can extend the workflows later as your chain grows and your team's requirements become clearer.
Verdict
Spawn for Windows is a practical choice for Web3 developers who want to start a Cosmos SDK chain without building the scaffolding from scratch. It is free, open source and includes module selection, GitHub Actions and end-to-end testing from the start. It suits developers who already know Go or are ready to learn it, and teams experimenting before a production launch. If your work centers on Ethereum tooling or a fully hand-built architecture, compare the alternatives in this catalog before you commit.