What Is Polygon CDK? Building Custom zk-Powered Chains

Polygon CDK, short for Chain Development Kit, is an open-source toolkit that lets developers launch their own zero-knowledge-powered layer-2 blockchain, using the same proving technology behind Polygon zkEVM, and optionally connect that chain to Polygon's broader ecosystem through the AggLayer.

What Polygon CDK gives developers

Similar in spirit to Optimism's OP Stack or Arbitrum's Orbit, Polygon CDK is Polygon's answer to "launch your own rollup without building the underlying cryptography and infrastructure from scratch." Teams using it get:

• Zero-knowledge proving infrastructure: Chains built with CDK use validity proofs rather than the fraud-proof-and-challenge-period model used by optimistic rollups, which generally allows for faster finality.
• Configurable data availability: Developers can choose to post full data on-chain (rollup mode) or use an alternative data availability setup for lower costs, similar to the trade-offs discussed in our validium vs. rollup comparison.
• Customization: Teams can adjust gas tokens, throughput parameters, and specific execution environment settings to fit their application's needs.
• AggLayer connectivity: Chains built with CDK can opt into Polygon's AggLayer, a system designed to unify liquidity and state across participating chains.

Why connect to the AggLayer at all

Launching an independent chain solves throughput and customization problems but reintroduces the liquidity fragmentation issue discussed in our piece on rollup interoperability — a new chain starts with no liquidity, no established user base, and no native way to interact with assets on other chains.

Polygon's AggLayer is meant to address this specifically for CDK chains (and other participating chains), aiming to let assets and state move between connected chains with something closer to the atomicity and speed of transactions on a single chain, rather than requiring slow, separate bridge transactions. This is Polygon's specific answer to the fragmentation problem that affects the broader modular/rollup landscape.

CDK vs. building fully custom infrastructure

Factor	Polygon CDK	Fully custom-built chain
Development time	Weeks to months	Months to years
Proving technology	Provided, based on proven zkEVM tech	Must build or heavily adapt
Liquidity/interop path	AggLayer (opt-in)	Must build bridges independently
Flexibility	Configurable within CDK's parameters	Unlimited but fully custom

What this means for someone using a CDK-based chain

If you're using an application or chain built with Polygon CDK, it's worth checking whether it has actually connected to the AggLayer or is running as a fully standalone chain, since that materially affects how easily you can move assets to and from other parts of the Polygon ecosystem. As with any newer L2 or L3 infrastructure, also check the chain's specific sequencer setup and data availability configuration rather than assuming uniform security across every CDK deployment — the toolkit provides options, and each chain's team makes its own choices within it.

The technology underneath: shared zkEVM proving

Polygon CDK chains draw on the same zero-knowledge proving technology developed for Polygon zkEVM, meaning teams building with CDK benefit from proving infrastructure that's already been tested and refined in production on a major, established chain, rather than adopting entirely new, unproven cryptography. This is a meaningful advantage over building fully custom ZK infrastructure from scratch, since generating efficient, secure validity proofs is one of the most technically demanding parts of building a ZK-rollup, and reusing battle-tested code here significantly reduces both development time and security risk compared to writing new proving systems independently.

Who is actually using Polygon CDK

A range of projects across gaming, DeFi, and enterprise use cases have adopted Polygon CDK to launch their own chains, often specifically because they need dedicated blockspace or a custom gas token that a shared, general-purpose chain can't offer as easily. As with any custom chain framework, the specific list of live deployments and their scale changes over time, so checking current activity and TVL data for a given CDK-based chain — available on our chains page — is more informative than relying on a static list of announced projects, some of which may still be in earlier stages of development or lower usage than public announcements suggest.

Bottom line

Polygon CDK lowers the barrier to launching a custom, zero-knowledge-powered chain by providing proven proving infrastructure and configurable data availability options, similar in purpose to the OP Stack or Arbitrum Orbit but built around Polygon's zkEVM technology. Its distinguishing feature is optional connectivity to the AggLayer, Polygon's attempt to solve cross-chain liquidity fragmentation for its ecosystem. As always with app-specific or custom chains, check each deployment's actual configuration — data availability choice, sequencer setup, and AggLayer connectivity — rather than assuming defaults.