How Does Polygon Let Other Projects Launch Their Own Custom Blockchains?

Polygon gives developers a framework to build and launch their own blockchains that connect back to the Ethereum network. These chains are not forks or copies of Polygon itself. They are independent networks that projects control entirely, built using Polygon's Chain Development Kit, known as the CDK. As of 2026, Polygon has repositioned CDK from a self-serve open-source toolkit into a managed, enterprise-grade service, with real deployments running at scale from OKX, Immutable, and Astar Network. What Is the Polygon CDK? The Polygon CDK is a framework that lets teams build custom blockchains secured by zero-knowledge proofs and settled on Ethereum. Think of it as a modular construction kit. A project works with Polygon to configure the components it needs, then launches a chain that suits its specific use case. Each chain built with the CDK uses zero-knowledge proofs, a cryptographic method that lets one party prove something is true without revealing the underlying data. This keeps transactions verifiable and secure without posting all transaction data directly to Ethereum. One important distinction worth knowing: Polygon's own zkEVM product, which was a separate public chain, set to sunset on July 1, 2026. That is different from CDK-based custom chains, which remain fully active and are unaffected by that shutdown. Projects like X Layer and Immutable zkEVM run on CDK infrastructure, not on Polygon's deprecated zkEVM chain. Is the Polygon CDK Still Free and Open Source? This is where things have shifted significantly since CDK's early days. The underlying code remains open source under the GNU AGPL license on GitHub. However, Polygon has repositioned the product itself. As of 2026, Polygon's official documentation describes CDK as "Chain-as-a-service, not a self-serve kit." Projects work directly with Polygon Labs to design, build, and operate a bespoke chain. Implementation partners including Gateway and Conduit manage production deployments with enterprise SLAs and 24/7 support. This does not mean CDK is unavailable to non-enterprise teams. But the current product offering is a managed service, not a toolkit a team simply downloads and deploys independently. Teams evaluating CDK should factor in operational support, sequencer management, and infrastructure decisions as part of the equation, typically handled with Polygon and its partners. How Does a Custom Chain Actually Work? Every CDK chain settles its transactions on Ethereum. That means Ethereum's security backs the chain, even though the chain itself operates independently.