Bridging CATs to EVM (Gateways): How the Chia Network CAT Bridge Works

Key Takeaways

• The warp.green CAT Bridge connects Chia Asset Tokens to Ethereum and Base networks through a secure cross-chain messaging protocol¹
• Your CATs are locked on Chia in vault coins and minted as ERC-20 tokens on EVM chains — the process is fully reversible¹
• 11 professional validators secure the bridge using a 7-of-11 multisig system, with multiple independent security audits completed²
• Bridging takes 10–15 minutes and costs a 0.3% bridge tip plus small network fees and message tolls on each chain²
• The bridge supports XCH and any CAT following Chia’s official token standard, working with both Ethereum mainnet and Base L2¹

The Chia Network CAT bridge is a gateway system that lets you move your Chia Asset Tokens to Ethereum-compatible blockchains. Using the warp.green messaging protocol, you can lock CATs on Chia and receive wrapped versions as ERC-20 tokens on Ethereum or Base — then reverse the process whenever you want.

Understanding the Chia Network CAT Bridge

The Chia Network CAT bridge works differently than you might expect. Instead of creating a brand-new token from scratch, the bridge locks your original CATs in a special vault on the Chia blockchain. Once locked, it sends a message to the destination blockchain instructing it to create matching tokens there.

Think of it like a coat check at a restaurant. You hand over your coat (your CATs), get a ticket (the wrapped token), and can redeem that ticket later to get your original coat back. The coat never leaves the building, but you have proof you own it.

warp.green built this bridge on top of their cross-chain messaging protocol — a system that lets blockchains securely send messages to one another.⁴ This messaging layer is what makes the CAT bridge possible, but it can also support other apps beyond token bridging.

The Two-Part Bridge System

The warp.green ecosystem includes two separate bridge apps that work together. The ERC-20 Bridge brings Ethereum tokens like ETH and USDC onto Chia as CATs. The CAT Bridge does the opposite — taking Chia tokens and wrapping them as ERC-20s on Ethereum or Base.³ Because the locking and minting mechanisms work so differently on each chain, it makes sense for these to be separate apps. Each one is optimised for its specific blockchain.

Vault Coins Replace Traditional Smart Contracts

On most blockchain bridges, tokens get locked inside a smart contract. Chia’s bridge works differently. When you bridge CATs, they get locked in what’s called a vault coin.¹ This is a special type of coin created using Chialisp puzzles that can only be unlocked when the bridge receives the right message from the other chain — specifically, proof that the equivalent ERC-20 token has been burned.

The vault coin approach takes advantage of Chia’s coin set model, where everything is a coin rather than an account balance. This provides better security through sandboxing — each coin operates independently, so a problem with one vault coin cannot affect others.

How the Chia CAT Bridge Gateway Technology Works

When you bridge a CAT from Chia to an EVM chain, several things happen behind the scenes. Your wallet creates a transaction that spends your CAT coins and creates new vault coins locked with a special bridging puzzle. This transaction also includes a message specifying where you want the tokens to appear on the destination chain.

Next, the validators step in. The warp.green protocol uses 11 validators who constantly monitor both Chia and the EVM chains for bridge messages.² When they see your bridge transaction, they wait for enough block confirmations to make sure the transaction is final — that is 32 blocks on Chia (roughly 10 minutes) or 64 slots on Ethereum (roughly 13 minutes).³

Once confirmed, each validator signs the message and publishes their signature to Nostr, a decentralised messaging network. The bridge interface collects these signatures — it needs at least 7 of the 11 validators to agree.² With enough signatures gathered, the bridge can prove to the destination blockchain that the tokens were really locked on Chia.

Finally, a transaction is submitted to the EVM chain. This transaction includes all the validator signatures and instructs the WrappedCAT contract to mint new ERC-20 tokens to your Ethereum or Base wallet. The amount minted matches what you locked on Chia, minus the bridge tip.

The Validator Network Secures Your Assets

The 11 validators come from well-known teams across the Chia ecosystem, including groups like TibetSwap/FireAcademy, dexie, Chain HQ, SpaceScan.io, Ozone Wallet, Goby, and Primer Security.² Each validator runs independent infrastructure and was selected based on technical ability and experience with highly secure systems. The full validator list is publicly available in the warp.green documentation.

The multisig approach means an attacker would need to compromise 7 of the 11 validators simultaneously to manipulate the bridge. This is dramatically harder than attacking a single point of failure. Validators do not just sign messages blindly — they independently verify that tokens were actually locked before signing. They also earn a share of the bridge tip, which creates an economic incentive to maintain reliable infrastructure and protect the system’s reputation.

Nostr Provides Decentralised Coordination

The bridge uses Nostr relays to publish validator signatures rather than storing them on a centralised server. Nostr is a simple, open protocol for sharing messages without depending on any single company or platform.⁵ When a validator signs a bridge message, it publishes that signature as a short note to Nostr relays. The bridge interface can then fetch these signatures from multiple relays, providing redundancy — if one relay goes offline, signatures are still available from others.

Setting Up Your Wallets for CAT Bridging

Before you can bridge CATs, you need wallets on both sides. On the Chia side, you’ll need a wallet that supports WalletConnect or the Goby browser extension.⁶ The Chia reference wallet works well for this, as do wallets like Pawket and Ozone.

For the EVM side, MetaMask is the most popular choice. You’ll need to add the Base network to MetaMask if you want to bridge to Base instead of Ethereum mainnet. Base has significantly lower gas fees than Ethereum mainnet, making it a practical choice for most users.

Make sure you have enough funds for fees on both chains. On Chia, you’ll need a small amount of XCH for the network fee plus the 0.001 XCH message toll. On Ethereum or Base, you’ll need ETH for gas fees plus the 0.00001 ETH toll.² These tolls go to block farmers or miners — not to the bridge operators — and are there to prevent spam.

Connecting to the Bridge Interface

Head to warp.green/bridge and you’ll see options to connect both your Chia and EVM wallets. Click the connect buttons and approve the connection in each wallet. The bridge needs permission to read your balances and create transactions, but it cannot spend your tokens without you explicitly approving each one.

Once connected, select which direction you want to bridge — Chia to Base, Chia to Ethereum, Base to Chia, or Ethereum to Chia. Then choose which token you want to bridge from the dropdown. Only tokens that have been set up and vetted for bridging will appear in this list. If you use Chia Offers on Dexie or TibetSwap, bridging opens up a whole new world of ways to use Chia Offers across DeFi platforms.

Step-by-Step Guide to Bridging CATs

Let’s walk through bridging Spacebucks (a popular Chia CAT) from Chia to Base. First, enter the amount you want to bridge in the interface. The bridge will show you the expected fees and the amount you’ll receive after the bridge tip is deducted.

Click “Initiate Bridging” and your Chia wallet will pop up asking you to approve the transaction. Review the details carefully — make sure the destination address is correct and you’re sending to the right network. Once you approve, the transaction gets submitted to the Chia blockchain.

Now you wait. The bridge status screen shows a progress bar while validators wait for confirmations. After about 10 minutes, the validators will have independently verified your transaction, signed the message, and published their signatures to Nostr. The bridge interface automatically fetches those signatures and, once it has enough, prepares the final EVM transaction.

Your MetaMask wallet will pop up showing the gas fee for the Base transaction. Approve this to complete the bridge. After the Base transaction confirms, check your MetaMask — you’ll see the Wrapped Spacebucks as an ERC-20 token. The 0.3% bridge tip has already been deducted. These wrapped tokens work like any other ERC-20 on Base — you can trade them on decentralised exchanges, use them in DeFi protocols, or send them to other addresses.

Bridging Back to Chia

The reverse process works similarly. On the bridge interface, select the direction from Base to Chia, choose your wrapped token, and enter the amount. You’ll need to approve two transactions on the Base side — the first gives the bridge contract permission to burn your wrapped tokens, and the second actually executes the burn and sends the bridge message.

After validators confirm, you’ll complete an offer file on Chia to receive your original tokens back. The bridge creates a Chia offer file that unlocks the vault coins and sends the CATs to your wallet. This uses Chia’s peer-to-peer offer system, which is more private than having the bridge directly send tokens to you — and if something goes wrong with the offer, the vault coins remain safely locked.

Understanding Bridge Fees and Costs

Every bridge operation involves three types of costs. Network transaction fees go to miners or farmers on each blockchain — you pay gas on Ethereum or Base and a farming fee on Chia. These vary based on network congestion at the time of bridging.

Message tolls prevent spam attacks on the bridge. The toll is 0.001 XCH when bridging from Chia and 0.00001 ETH when bridging from Ethereum or Base.² These tolls go to the block producer — not to the bridge operators.

The bridge tip is 0.3% of the bridged amount and goes to the validators who secure the network. It is automatically deducted from the amount you receive, so you do not need to calculate it separately.

Calculating Your Total Costs

To put it in perspective: bridging $1,000 worth of tokens costs roughly $3 in bridge tip, a fraction of a dollar for the XCH toll, and $0.10–$0.50 in Base gas fees depending on network activity. That works out to around 0.35% total — competitive with many centralised exchange withdrawal fees. For smaller amounts, the fixed costs become a larger share of your total, so bridging is more economical for larger transactions.

Security Features That Protect Your Chia CAT Bridge Assets

The warp.green bridge went through extensive security testing before launch. Hacken, a blockchain security firm specialising in smart contract audits, reviewed the Solidity contracts and gave them a perfect 10/10 score across security, code quality, test coverage, and documentation.⁷ The audit identified 7 potential issues, and 6 were fully resolved or mitigated before launch.

Chia Network Inc. reviewed the Chialisp puzzles on the Chia side of the bridge. Shortly after the mainnet launch, Zellic — another independent blockchain security company — performed a second audit of the Solidity contracts.² The bridge also maintains a public bug bounty programme where security researchers can report vulnerabilities for rewards.

The bridge contracts are immutable once deployed — no one can change how they work, not even the developers. The only upgradeable component is the warp.green messaging layer itself, which is controlled by a multisig of validator cold wallets and would require a transparent governance process to change.

Understanding Bridge Risks

No bridge is completely risk-free, and the warp.green documentation is transparent about what those risks are. Validator compromise is one risk — if attackers simultaneously gained control of 7 validators, they could potentially manipulate the bridge. The diverse, independent selection of validator teams is designed to make this extremely difficult in practice.

Smart contract vulnerabilities could in theory allow hackers to exploit bugs in the code. The two independent audits significantly reduce this risk, but no audit can guarantee code is entirely bug-free. Blockchain consensus failures on either chain could also cause temporary issues. The confirmation requirements — 32 blocks on Chia and 64 slots on Ethereum — provide a strong buffer against this. The bridge has been running on mainnet since May 2024 with no major incidents.⁷

Supported Tokens and Networks

The CAT Bridge supports XCH (Chia’s native currency) and any CAT following Chia’s official token standard.¹ At launch, supported tokens included USDS, milliETH, wUSDC, and community tokens like Spacebucks. Not every CAT is listed in the bridge interface — the warp.green team maintains a curated list to protect users from scam or incompatible tokens.

On the EVM side, the bridge connects to Ethereum mainnet and Base. Base is an Ethereum Layer 2 network launched by Coinbase that offers much lower transaction fees than mainnet. For most users, bridging to Base makes more economic sense unless they specifically need tokens on Ethereum for a particular DeFi application.

Note that “warped” is the term warp.green uses to describe tokens that have been bridged through their system — you may see this terminology used across Chia DEXs like TibetSwap and Dexie when trading wrapped assets.

Creating Wrapped Tokens for New CATs

CAT creators can make their tokens bridgeable by deploying a WrappedCAT contract on Base. The process involves deploying the contract, testing it with small transfers, and submitting pull requests to the bridge’s GitHub repositories. The warp.green team reviews each submission to confirm the token is legitimate before adding it to the bridge interface.

How Chia’s Unique Architecture Enables Better Bridges

Chia’s coin set model and Chialisp programming language provide real advantages for bridge security. In the coin set model, each coin is an independent object with its own puzzle governing how it can be spent.⁸ This is fundamentally different from account-based blockchains where all tokens in an account share the same security model.

When CATs are locked in bridge vaults, each vault is a separate coin with its own independent security. If there were a bug affecting one vault, it would not automatically compromise all vaults. This compartmentalisation limits the blast radius of any potential exploit. Chialisp’s deterministic execution also means bridge puzzles will always behave exactly the same way — no surprises from runtime environments or external dependencies.

As yakuhito from TibetSwap and FireAcademy — one of the warp.green validators — noted when the bridge launched: the ability to use Chia’s native offer mechanism for the final step of unwrapping adds a layer of user control and privacy that most bridge designs simply do not have.

Atomic Offers Provide Extra Security on Unwrapping

When you bridge tokens back from an EVM chain to Chia, the final step uses Chia’s atomic offer system.⁹ Atomic offers are peer-to-peer swaps that either complete fully or not at all — there is no way for one party to receive tokens without fulfilling their side of the exchange. This is more secure than having the bridge directly push tokens to your wallet, and it means you stay in control throughout the entire process.

Use Cases for Bridged CATs

Why would you want to bridge your CATs to Ethereum or Base? The main reason is accessing DeFi protocols and decentralised exchanges that exist on those networks. By wrapping Chia tokens as ERC-20s, you can use them in Uniswap, Curve, Aave, and hundreds of other applications that have no native Chia support.

Some traders bridge tokens to take advantage of price differences between Chia DEXs and Ethereum or Base DEXs. If a token trades at meaningfully different prices across chains, the bridge creates an arbitrage path. The bridge also makes it easier to move tokens onto platforms that primarily support ERC-20 assets, expanding the reach of Chia’s ecosystem considerably. You can read more about how the Chia bridge validator programme was launched and how Chia Network has built out its interoperability infrastructure.

Real-World Bridge Activity

Since launching in May 2024, the warp.green bridge has processed thousands of transactions. The first transaction completed on mainnet was for wmilliETH — ETH bridged onto Chia via the ERC-20 Bridge, with the first settled offer on Dexie confirmed shortly after launch.⁷ Liquidity pools for wrapped assets on TibetSwap and Dexie emerged quickly, creating active trading pairs for warped ETH, USDC, and native Chia tokens.

Comparing the Chia CAT Bridge to Other Bridge Solutions

Most bridges use either trusted custodians (centralised) or validator sets (decentralised). The warp.green bridge falls firmly in the decentralised category with its 11-validator multisig. Compared to general-purpose bridges like Wormhole, which uses 19 validators across dozens of chains, warp.green keeps a smaller and more focused validator set dedicated specifically to Chia-EVM connections. This focus reduces complexity and potential attack surfaces.

The Immutability Advantage

Unlike many bridges that can be upgraded or paused by administrators, the warp.green bridge contracts are immutable. Once deployed, the rules for minting and burning wrapped tokens cannot be changed. This provides a strong guarantee — you know exactly how the bridge will behave, today and in the future. The only upgradeable component is the warp.green messaging layer, and even that requires agreement from multiple validator cold wallets stored in multisig vaults.

Conclusion

The Chia Network CAT bridge is a well-designed, audited gateway that opens Chia’s ecosystem to the wider world of Ethereum and Base. By locking CATs in secure vault coins and minting corresponding ERC-20 tokens, it creates a reliable two-way connection between these blockchain ecosystems. With 11 independent validators, two professional security audits, immutable contracts, and transparent documentation, it is one of the more trustworthy bridge implementations in the broader crypto space. Bridging always carries inherent risks — validator compromise, smart contract bugs, and chain-level failures are real possibilities — but the architecture minimises each one thoughtfully. Whether you’re looking to access Ethereum DeFi, take advantage of cross-chain liquidity, or simply expand where your Chia tokens can be used, the CAT bridge gives you a practical and secure way to do it.

Chia CAT Bridge FAQs

What is the Chia Network CAT bridge?

The Chia Network CAT bridge is a gateway system that lets you lock Chia Asset Tokens on the Chia blockchain and receive wrapped versions as ERC-20 tokens on Ethereum or Base, using the warp.green cross-chain messaging protocol secured by 11 independent validators requiring 7 signatures to process any transaction.¹

How long does it take to bridge CATs between Chia and Ethereum?

Bridging CATs takes 10–15 minutes depending on direction — validators wait for 32 Chia blocks (~10 minutes) when bridging from Chia, or 64 Ethereum slots (~13 minutes) when bridging from an EVM chain, to ensure finality before processing the message.³

What are the fees for using the Chia CAT bridge?

The bridge charges a 0.3% bridge tip that is split among validators, plus network transaction fees on both chains and small message tolls of 0.001 XCH from Chia or 0.00001 ETH from EVM chains to prevent spam — the tolls go to block producers, not the bridge.²

Which wallets work with the Chia Network CAT bridge?

On the Chia side you need a wallet supporting WalletConnect or the Goby browser extension, such as the Chia reference wallet, Pawket, or Ozone — on the EVM side, MetaMask and other standard Web3 wallets configured for Ethereum mainnet or Base both work.⁶

Is the Chia CAT bridge safe to use?

The warp.green bridge has been independently audited by both Hacken and Zellic, with Chia Network Inc. reviewing the Chialisp puzzles, uses 11 independent validators requiring a 7-of-11 supermajority to process transactions, and deploys immutable contracts — though like all bridges, risks from validator compromise and smart contract vulnerabilities exist and should be understood before bridging large amounts.²

Chia CAT Bridge Citations

1. warp.green Documentation. (n.d.). CAT Bridge. Retrieved from https://docs.warp.green/developers/cat-bridge
2. warp.green Documentation. (n.d.). FAQ. Retrieved from https://docs.warp.green/
3. XCH.today. (2024, May 10). warp.green Updates: Bridge Sneak Peek and Developer Docs. Retrieved from https://xch.today/2024/05/10/warp-green-updates-bridge-sneak-peek-and-developer-docs/
4. warp.green. (n.d.). warp.green Protocol Overview. Retrieved from https://www.warp.green/
5. warp.green Documentation. (n.d.). warp.green Protocol — Collecting Signatures. Retrieved from https://docs.warp.green/developers/warp.green/collecting-signatures
6. Chia Documentation. (n.d.). XCH Bridge Guide. Retrieved from https://docs.chia.net/bridge-guide/
7. XCH.today. (2024, May 22). warp.green Launches Ethereum Bridge. Retrieved from https://xch.today/2024/05/22/warp-green-launches-ethereum-bridge/
8. Chia Documentation. (n.d.). Coin Set Intro. Retrieved from https://docs.chia.net/coin-set-intro/
9. Chia Documentation. (n.d.). Introduction. Retrieved from https://docs.chia.net/chia-blockchain/introduction/