> ## Documentation Index
> Fetch the complete documentation index at: https://cobo.com/products/agentic-wallet/manual/llms.txt
> Use this file to discover all available pages before exploring further.

# Chains and chain IDs

> How blockchains are identified, and which chains Cobo Agentic Wallet supports.

## What is a blockchain

A blockchain is a network of computers that jointly maintain a shared record of transactions. Each blockchain is its own independent network — a token on Ethereum and a token on Polygon are not interchangeable unless explicitly moved between them.

When you send a transaction or interact with a protocol, you do so on a specific chain. Sending tokens to the wrong chain means they can be lost.

## Supported chains

Cobo Agentic supports two categories of chains: EVM-compatible chains and Solana. These categories differ in address format, token standard, and contract interaction model — see [EVM vs. Solana](#evm-vs-solana) for a full comparison.

### EVM chains

EVM chains follow the same technical rules as Ethereum and use a numeric chain ID to identify each network.

Each EVM chain has a unique numeric **chain ID** so tools know which network you're on.

| Chain                      | Chain identifier | EVM chain ID |
| -------------------------- | ---------------- | ------------ |
| Ethereum mainnet           | `ETH`            | `1`          |
| Base mainnet               | `BASE_ETH`       | `8453`       |
| Polygon PoS mainnet        | `MATIC`          | `137`        |
| Arbitrum One               | `ARBITRUM_ETH`   | `42161`      |
| Optimism mainnet           | `OPT_ETH`        | `10`         |
| Avalanche C-Chain          | `AVAXC`          | `43114`      |
| BNB Smart Chain            | `BSC_BNB`        | `56`         |
| Tempo mainnet              | `TEMPO_TEMPO`    | —            |
| Ethereum Sepolia (testnet) | `SETH`           | `11155111`   |
| Base Sepolia (testnet)     | `TBASE_SETH`     | `84532`      |
| Tempo testnet (testnet)    | `TTEMPO_TEMPO`   | —            |

### Solana

Solana uses a cluster name rather than a numeric chain ID to identify each network.

| Cluster                 | Chain identifier |
| ----------------------- | ---------------- |
| Solana mainnet          | `SOL`            |
| Solana devnet (testnet) | `SOLDEV_SOL`     |

## EVM vs. Solana

Cobo supports both EVM-compatible chains and Solana. These two ecosystems work differently:

|                          | EVM (Ethereum, Base, Polygon)    | Solana                      |
| ------------------------ | -------------------------------- | --------------------------- |
| Address format           | `0x`-prefixed hex, 42 characters | Base58, \~44 characters     |
| Token standard           | ERC-20                           | SPL                         |
| How contracts are called | Encoded function data            | Instructions + account list |
| Fee unit                 | Gwei (fractions of ETH or MATIC) | Lamports (fractions of SOL) |

See [Smart contracts](/products/agentic-wallet/manual/learn/smart-contracts) for more on how contract calls work on each chain type.

## Layer 2 chains

Some EVM chains — including Base, Arbitrum, and Optimism — are Layer 2 (L2) chains. They process transactions faster and more cheaply than Ethereum mainnet by handling activity off the main chain, then periodically recording a summary back to Ethereum for security.

From a user's perspective, L2 chains work just like Ethereum: same address format, same token standards, same contract interaction model. The main practical differences are:

* Gas fees on L2 are typically 10–100× cheaper than Ethereum mainnet.
* Bridge exits back to Ethereum vary by rollup type: optimistic rollups (Base, Optimism) require a challenge period of up to 7 days; ZK rollups can settle in minutes to hours.
* Protocols like Uniswap deploy separate contracts on each L2 — the contract addresses differ across networks.