> For the complete documentation index, see [llms.txt](https://docs.astralbeam.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.astralbeam.io/using-astralbeam/bridging-evm-to-casper.md).

# Bridging EVM to Casper

This guide walks you through bridging ERC-20 tokens from an EVM chain (Ethereum, Base, etc.) to Casper Network.

## Overview

When you bridge from EVM to Casper:

1. **Lock**: Your ERC-20 tokens are locked in the MultiSigLocker contract
2. **Finality**: The bridge waits for Ethereum finality (\~13 minutes)
3. **Attestation**: Relayers verify the lock event and collect signatures
4. **Mint**: CEP-18 tokens are minted to your Casper address

## Prerequisites

* Both wallets connected (see [Connecting Wallets](/using-astralbeam/connecting-wallets.md))
* ERC-20 tokens to bridge (see [Getting Testnet Tokens](/using-astralbeam/getting-testnet-tokens.md))
* ETH for gas fees on the source chain
* Small bridge fee (0.0001 ETH)

## Step-by-Step Guide

### Step 1: Select Source Network

1. Go to [astralbeam.io](https://astralbeam.io)
2. In the "From" section, ensure an EVM network is selected
3. Click the network selector to change networks if needed
4. Available networks: Ethereum (Sepolia), Base (Sepolia), etc.

### Step 2: Select Token

1. Click "Select token" in the token input area
2. A modal will display available bridgeable tokens
3. Choose the token you want to bridge (e.g., USDC, WETH, LINK)
4. Your token balance will be displayed

### Step 3: Enter Amount

1. Enter the amount of tokens to bridge
2. The interface will show:
   * Your available balance
   * Estimated receive amount on Casper
3. Ensure you have enough tokens and don't exceed your balance

### Step 4: Review Transaction

1. Click "Review Bridged Transfer"
2. A modal displays the transaction summary:

| Field     | Description                             |
| --------- | --------------------------------------- |
| From      | Source network (e.g., Ethereum Sepolia) |
| To        | Destination network (Casper Testnet)    |
| Amount    | Token amount being bridged              |
| Recipient | Your Casper public key                  |

3. Verify all details are correct

### Step 5: Approve Token Spending

1. Click "Start Bridged Transfer"
2. **First Transaction - Approval**:
   * MetaMask will popup requesting token approval
   * This allows the locker contract to spend your tokens
   * Review the approval amount
   * Click "Confirm" in MetaMask
3. Wait for the approval transaction to confirm

### Step 6: Confirm Lock Transaction

1. **Second Transaction - Lock**:
   * MetaMask will popup for the lock transaction
   * This locks your tokens in the bridge contract
   * The transaction includes a 0.0001 ETH bridge fee
   * Click "Confirm" in MetaMask
2. Wait for the lock transaction to confirm

### Step 7: Wait for Finality

After the lock transaction confirms:

1. The modal shows "Wait for Finality" as active
2. **Why wait?** Ethereum needs \~64 blocks (\~13 minutes) for finality
3. This protects against chain reorganizations
4. Progress indicator shows estimated time remaining

You can safely close the modal - your transaction is tracked automatically.

### Step 8: Relayer Processing

Once finality is reached:

1. Relayers detect the finalized lock event
2. Each relayer verifies the MPT proof independently
3. Relayers sign attestations and exchange via P2P
4. When M-of-N signatures are collected, mint is submitted

### Step 9: Receive Tokens on Casper

1. The leader relayer submits the mint transaction
2. CEP-18 tokens are minted to your Casper address
3. The modal shows "Completed" status
4. View your tokens in Casper Wallet or CSPR.live

## Transaction Progress Steps

| Step | Status              | Description                        |
| ---- | ------------------- | ---------------------------------- |
| 1    | Approve Token       | Allow locker to spend tokens       |
| 2    | Lock Tokens         | Lock tokens in bridge contract     |
| 3    | Wait for Finality   | \~13 minutes for Ethereum finality |
| 4    | Relayer Attestation | Relayers verify and sign           |
| 5    | Mint on Casper      | CEP-18 tokens minted               |

## Viewing Your Bridged Tokens

### On CSPR.live

1. Go to [testnet.cspr.live](https://testnet.cspr.live)
2. Search for your Casper account
3. Navigate to "Tokens" tab
4. Your bridged CEP-18 tokens will appear

### In Casper Wallet

1. Open Casper Wallet extension
2. Your token balance should update automatically
3. If not visible, you may need to add the token manually

## Troubleshooting

### Transaction Stuck on "Approval"

* Check MetaMask for pending requests
* Ensure you have enough ETH for gas
* Try increasing gas price if network is congested

### Transaction Stuck on "Lock"

* Verify approval transaction completed
* Check MetaMask for the second transaction request
* Ensure sufficient ETH for gas + 0.0001 ETH fee

### Long Finality Wait

* Ethereum finality takes \~13 minutes (64 blocks)
* This is normal and ensures security
* Progress is saved - you can close and return later

### Tokens Not Appearing on Casper

* Wait for the full process to complete
* Check the Transactions page for status
* Verify the correct Casper address was used
* Check CSPR.live for your account's token balances

## Gas and Fees

| Fee Type        | Amount     | Paid By   |
| --------------- | ---------- | --------- |
| Approval Gas    | Variable   | You (ETH) |
| Lock Gas        | Variable   | You (ETH) |
| Bridge Fee      | 0.0001 ETH | You       |
| Casper Mint Gas | \~2.5 CSPR | Relayers  |

## Example: Bridging 10 USDC

1. Connect MetaMask (Sepolia) and Casper Wallet
2. Select "Ethereum (Sepolia)" as source
3. Select USDC from token list
4. Enter "10" as amount
5. Review: 10 USDC → 10 USDC (CEP-18)
6. Approve USDC spending in MetaMask
7. Confirm lock transaction in MetaMask
8. Wait \~15-20 minutes total
9. Receive 10 USDC (CEP-18) on Casper


---

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