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Working with Tokens
ZRC-20

ZRC-20 is a token standard integrated into ZetaChain's omnichain smart contract platform. With ZRC-20, developers can build dApps that orchestrate native assets on any connected chain. This makes building Omnichain DeFi protocols and dApps such as Omnichain DEXs, Omnichain Lending, Omnichain Portfolio Management, and anything else that involves fungible tokens on multiple chains from a single place extremely simple — as if they were all on a single chain.

Native gas tokens of connected blockchains and whitelisted ERC-20 tokens can be deposited to ZetaChain as ZRC-20 tokens. During the deposit process, the native/ERC-20 tokens are transferred to and locked in the TSS address/ERC-20 custody contract and ZRC-20 tokens are minted on ZetaChain and deposited to the recipient address.

ZRC-20 tokens can be withdrawn from ZetaChain to connected blockchains. During the withdrawal process, ZRC-20 tokens are burnt on ZetaChain and native/ERC-20 tokens are transferred to the recipient address on the connected chain from a TSS address/ERC-20 custody contract.

ZRC-20 tokens can only be minted by the ZetaChain protocol. An ERC-20 token deployed on ZetaChain does not have the properties of ZRC-20 and can't be withdrawn from ZetaChain to a connected chain.

The "same" ERC-20 token from two connected blockchains is represented as two different ZRC-20 tokens on ZetaChain. For example, USDT from Ethereum is represented as ZRC-20 USDT from Ethereum, and USDT from BSC is represented as ZRC-20 USDT from BSC. They are not considered the same asset by ZetaChain, but they can be swapped. That's how the transfer of the "same" ERC-20 asset can be implemented on ZetaChain: by depositing an ERC-20 (chain A), swapping this ZRC-20 (chain A) to an ZRC-20 (chain B), and withdrawing the ZRC-20 (chain B) to chain B as ERC-20.

A list of currently supported assets:

Source: https://zetachain.blockpi.network/lcd/v1/public/zeta-chain/fungible/foreign_coins

New assets can be added or removed by broadcasting a transaction with a corresponding message of the fungible module on ZetaChain.

At a high-level, ZRC-20 tokens are an extension of the standard ERC-20 (opens in a new tab) tokens found in the Ethereum ecosystem, ZRC-20 tokens have the added ability to manage assets on all ZetaChain-connected chains. Any fungible token, including Bitcoin, ETH, other gas assets and ERC-20-equivalents on other chains, may be represented on ZetaChain as a ZRC-20 and orchestrated as if it were any other fungible token (like an ERC-20).

When depositing to or withdrawing from ZetaChain, the protocol requires a certain number of confirmations on the connected chain before the transaction is considered final. The number of confirmations required is different for each chain. You can check the number of confirmations in the table below:

These values are stored in the state of ZetaChain and are used by ZetaClient (the program that observer-signer validators run) as recommended values of confirmations. In some cases ZetaClient can use a higher number of confirmations, for example, when the value transfer exceeds a specified amount.

Each ZRC-20 has a total cap on the number of deposited tokens that the protocol can accept. Any assets beyond this deposited to ZetaChain from connected chains will be returned to the sender. You can view the caps on the explorer here (opens in a new tab).