> For the complete documentation index, see [llms.txt](https://crosschain-docs.gitbook.io/crosschain-docs-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://crosschain-docs.gitbook.io/crosschain-docs-docs/chain-id-checks-for-frequent-bridge-users.md).

# Chain ID Checks for Frequent Bridge Users

A chain ID is the numeric network domain a wallet and EVM transaction use to select where a signature is valid. Before signing, compare the wallet’s active chain ID with the bridge’s requested source chain; for a transfer from Ethereum to Manta Pacific, those values should be 1 and 169, respectively.

Keep these checks in your transfer routine:

* Check the wallet’s active chain ID immediately before signing.
* Match it to the selected source network, not the destination.
* After switching, confirm the wallet and bridge agree before submitting.

### What does a chain ID check actually protect?

A chain ID check prevents a transaction intended for one EVM network from being signed under another network’s domain. EIP-155 incorporates the chain ID into the transaction signing hash; the resulting signature is therefore not ordinarily valid for replay on a different chain ID.

For a legacy EIP-155 transaction, the signer hashes the six transaction fields plus the chain ID and two zero values. Its signature’s v value encodes the chain ID and recovery parity: v = chain ID × 2 + 35 + parity. Typed transactions instead carry the chain ID in their signed payload. This protects against cross-chain replay when chains use different IDs; it does not verify that the RPC endpoint or displayed network is honest.

### How should you check the network before signing?

Read the wallet provider’s current chain ID, usually through eth\_chainId, and compare it with the source chain expected by the bridge. The method returns a hexadecimal quantity, so Ethereum mainnet appears as 0x1 and Manta Pacific as 0xa9; a wallet may display the same values in decimal as 1 and 169.

When the IDs differ, switch the wallet to the required source network, then read the active ID again before signing. If the wallet reports an unknown-chain error, it may need the network added first. Don’t treat a successful switch request as proof the switch completed: wallet prompts can be rejected, delayed, or superseded by another tab.

A chain ID is a useful domain label, not a complete chain fingerprint. Two networks can share an ID, and a compromised or misconfigured RPC can report the expected ID while serving the wrong chain state. For high-value transfers, also verify the network name and trusted RPC configuration in the wallet, then review the transaction’s destination and calldata.

### What does this change in a bridge transfer?

The wallet signs on the source chain, so check that chain before authorizing the bridge’s deposit or initiation transaction. For example, if you are sending ETH from Ethereum to Manta Pacific, the source should be Ethereum mainnet, ID 1; Manta Pacific, ID 169, is the destination where the bridged funds are expected to arrive.

At that point, the [Manta Bridge route](https://oraclewire.pages.dev/manta-bridge-check-deposit-support-before-choosing/) is a concrete example: select the direction and asset, check the source network in the wallet, and sign only after it matches the route. The destination ID does not change the chain on which your source transaction is signed; it helps identify where the transfer should complete.

Switching to the destination too early can make the source transaction unavailable or cause the bridge interface to request a different route. I would follow the bridge’s source-first flow and avoid extra network switches: each switch costs time and adds another chance to approve a transaction on the wrong chain, while the chain ID itself does not change gas fees.

### Which failures should change your next step?

If the wallet shows the wrong ID, stop before signing and switch back to the route’s source network. If the ID matches but the wallet shows an unexpected recipient or contract, reject the request; a correct chain ID cannot validate transaction calldata or prove that the bridge interface is legitimate.

If a transaction was already signed but not broadcast, inspect its chain ID and transaction details before sending it. If it was broadcast, check its status on the source chain’s trusted explorer; a failed or pending source transaction is different from a successful source transaction whose destination transfer is still processing.

### Common follow-up questions

#### Does changing networks change my wallet address?

No. The same EVM account address can exist on multiple chains because it is derived from the account’s public key. Its balances and transaction history are chain-specific, though, so an address with ETH on Ethereum does not imply it holds ETH on Manta Pacific.

#### Is chain ID the same as a network name?

No. A network name is a human-readable label; the chain ID is a numeric signing domain used by EVM transactions. Names can be duplicated or configured incorrectly, so compare the ID as well as the wallet’s network details before authorizing a bridge transaction.

#### Can matching chain IDs guarantee the RPC is safe?

No. The ID identifies the reported transaction domain, but an RPC endpoint can be misconfigured or malicious. Use a trusted endpoint and verify the chain’s explorer and transaction details when the amount makes that extra check worthwhile.

#### Do I need to sign on the destination chain too?

Usually, the bridge initiation is signed on the source chain; destination execution may be handled by the bridge process. Follow the route’s prompts and inspect any additional wallet request rather than assuming it is required. A destination-chain signature should make sense for the action being requested.

For fast repeat transfers, the reliable shortcut is a single source-chain ID check immediately before signing, followed by a quick review of the transaction destination.