# Table of Contents

- [Anvil – foundry - Ethereum Development Framework](#anvil-foundry-ethereum-development-framework)
- [Forking – foundry - Ethereum Development Framework](#forking-foundry-ethereum-development-framework)
- [State management – foundry - Ethereum Development Framework](#state-management-foundry-ethereum-development-framework)
- [Custom methods – foundry - Ethereum Development Framework](#custom-methods-foundry-ethereum-development-framework)

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# Anvil – foundry - Ethereum Development Framework

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Anvil[](https://www.getfoundry.sh/anvil#anvil)

-----------------------------------------------

Anvil is a fast local Ethereum node for development and testing. It runs entirely in-memory and supports forking from any EVM-compatible chain.

### Key capabilities[](https://www.getfoundry.sh/anvil#key-capabilities)

| Feature | Description |
| --- | --- |
| **Local development** | Start a local node with pre-funded accounts and instant mining |
| **Forking** | Fork mainnet or any chain at a specific block |
| **State management** | Dump and load chain state for reproducible testing |
| **Custom RPC methods** | Impersonate accounts, manipulate time, and control mining |
| **Tracing** | Debug transactions with full execution traces |

### Common workflows[](https://www.getfoundry.sh/anvil#common-workflows)

Start local nodeCustom accounts

    $ anvil

Fork mainnetFork at block

    $ anvil --fork-url https://ethereum.reth.rs/rpc

Auto-impersonate

    $ anvil --auto-impersonate

### Default accounts[](https://www.getfoundry.sh/anvil#default-accounts)

Anvil generates 10 development accounts with 10,000 ETH each. The default mnemonic is:

    test test test test test test test test test test test junk
    

You can customize accounts with `--accounts`, `--balance`, and `--mnemonic`.

### Learn more[](https://www.getfoundry.sh/anvil#learn-more)

*   [Forking](https://www.getfoundry.sh/anvil/forking)
     — Fork mainnet and other chains
*   [State management](https://www.getfoundry.sh/anvil/state-management)
     — Dump and load chain state
*   [Custom methods](https://www.getfoundry.sh/anvil/custom-methods)
     — Impersonation, mining control, and time manipulation

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# Forking – foundry - Ethereum Development Framework

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Forking[](https://www.getfoundry.sh/anvil/forking#forking)

-----------------------------------------------------------

Anvil can fork any EVM-compatible chain, allowing you to test against real-world state without deploying to a live network.

### Basic forking[](https://www.getfoundry.sh/anvil/forking#basic-forking)

    $ anvil --fork-url https://ethereum.reth.rs/rpc

You can also fork from a specific point in the chain's history:

At blockAt transaction

    $ anvil --fork-url https://ethereum.reth.rs/rpc --fork-block-number 18000000

### Chain configuration[](https://www.getfoundry.sh/anvil/forking#chain-configuration)

When forking, Anvil inherits the chain ID from the remote endpoint by default.

Override chain ID

    $ anvil --fork-url https://ethereum.reth.rs/rpc --chain-id 1337

Specify hardfork

    $ anvil --fork-url https://ethereum.reth.rs/rpc --hardfork cancun

### Rate limiting[](https://www.getfoundry.sh/anvil/forking#rate-limiting)

RPC providers often rate-limit requests. Anvil handles this automatically but you can tune the behavior:

Set compute units per second

    $ anvil --fork-url $RPC_URL --compute-units-per-second 100

Disable rate limiting

    $ anvil --fork-url $RPC_URL --no-rate-limit

Set retry count

    $ anvil --fork-url $RPC_URL --retries 10

### Caching[](https://www.getfoundry.sh/anvil/forking#caching)

Anvil caches forked state to disk at `~/.foundry/cache/rpc/<chain>/<block>/` to speed up subsequent runs.

Disable storage caching

    $ anvil --fork-url $RPC_URL --no-storage-caching

### Custom headers[](https://www.getfoundry.sh/anvil/forking#custom-headers)

Some RPC providers require authentication headers:

Add custom header

    $ anvil --fork-url $RPC_URL --fork-header "Authorization: Bearer $TOKEN"

### L2 support[](https://www.getfoundry.sh/anvil/forking#l2-support)

Anvil supports L2-specific features:

Enable Optimism features

    $ anvil --fork-url https://mainnet.optimism.io --optimism

Enable Celo features

    $ anvil --fork-url https://forno.celo.org --celo

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# State management – foundry - Ethereum Development Framework

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State management[](https://www.getfoundry.sh/anvil/state-management#state-management)

--------------------------------------------------------------------------------------

Anvil can save and restore chain state, enabling reproducible test scenarios and faster development workflows.

### Dumping state[](https://www.getfoundry.sh/anvil/state-management#dumping-state)

Save the current state when Anvil exits:

Dump state on exit

    $ anvil --dump-state state.json

Dump to a directory

    $ anvil --dump-state ./states/

### Loading state[](https://www.getfoundry.sh/anvil/state-management#loading-state)

Start from a previously saved state:

Load from state file

    $ anvil --load-state state.json

### Combined state file[](https://www.getfoundry.sh/anvil/state-management#combined-state-file)

Use `--state` to both load and dump from the same file:

Persist state across restarts

    $ anvil --state state.json

This loads the state on startup (if the file exists) and saves it on exit.

### Periodic snapshots[](https://www.getfoundry.sh/anvil/state-management#periodic-snapshots)

Save state at regular intervals to prevent data loss:

Dump state every 60 seconds

    $ anvil --state state.json --state-interval 60

### Historical states[](https://www.getfoundry.sh/anvil/state-management#historical-states)

By default, Anvil only keeps the latest state. Enable historical state preservation for debugging:

Preserve historical states

    $ anvil --preserve-historical-states --dump-state state.json

Limit persisted states

    $ anvil --max-persisted-states 100

### Memory management[](https://www.getfoundry.sh/anvil/state-management#memory-management)

For long-running instances, prune historical state to reduce memory usage:

Prune history (keep 10 states)

    $ anvil --prune-history 10

Prune all history

    $ anvil --prune-history

### Genesis configuration[](https://www.getfoundry.sh/anvil/state-management#genesis-configuration)

Initialize Anvil with a custom genesis file:

Use custom genesis

    $ anvil --init genesis.json

The genesis file follows the standard Ethereum genesis format with `alloc`, `difficulty`, `gasLimit`, and other fields.

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# Custom methods – foundry - Ethereum Development Framework

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Custom methods[](https://www.getfoundry.sh/anvil/custom-methods#custom-methods)

--------------------------------------------------------------------------------

Anvil exposes custom RPC methods beyond the standard Ethereum JSON-RPC API. These methods are useful for testing scenarios that require account impersonation, time manipulation, or mining control.

### Account impersonation[](https://www.getfoundry.sh/anvil/custom-methods#account-impersonation)

Impersonate any account to send transactions without its private key:

Impersonate an account

    $ cast rpc anvil_impersonateAccount $ADDRESS

Send transaction as impersonated account

    $ cast send $CONTRACT "transfer(address,uint256)" $TO $AMOUNT --from $ADDRESS --unlocked

Stop impersonating

    $ cast rpc anvil_stopImpersonatingAccount $ADDRESS

Start Anvil with auto-impersonation enabled:

Enable auto-impersonation

    $ anvil --auto-impersonate

### Mining control[](https://www.getfoundry.sh/anvil/custom-methods#mining-control)

Control when blocks are mined:

Disable automatic mining

    $ anvil --no-mining

Mine a single block

    $ cast rpc anvil_mine

Mine multiple blocks

    $ cast rpc anvil_mine 10

Set block interval (seconds)

    $ anvil --block-time 12

Enable interval mining via RPC

    $ cast rpc evm_setIntervalMining 12

Resume automatic mining

    $ cast rpc evm_setAutomine true

### Time manipulation[](https://www.getfoundry.sh/anvil/custom-methods#time-manipulation)

Control the blockchain's perception of time:

Increase time by seconds

    $ cast rpc evm_increaseTime 3600

Set next block timestamp

    $ cast rpc evm_setNextBlockTimestamp 1700000000

Mine block with new timestamp

    $ cast rpc evm_mine

### State snapshots[](https://www.getfoundry.sh/anvil/custom-methods#state-snapshots)

Create and restore chain state snapshots during a session:

Create snapshot

    $ cast rpc evm_snapshot

Revert to snapshot

    $ cast rpc evm_revert $SNAPSHOT_ID

Snapshots return an ID that you use to revert. Reverting removes the snapshot.

### Balance and code manipulation[](https://www.getfoundry.sh/anvil/custom-methods#balance-and-code-manipulation)

Modify account state directly:

Set account balance

    $ cast rpc anvil_setBalance $ADDRESS 0xDE0B6B3A7640000

Set account nonce

    $ cast rpc anvil_setNonce $ADDRESS 0x10

Set contract code

    $ cast rpc anvil_setCode $ADDRESS $BYTECODE

Set storage slot

    $ cast rpc anvil_setStorageAt $ADDRESS $SLOT $VALUE

### Chain configuration[](https://www.getfoundry.sh/anvil/custom-methods#chain-configuration)

Modify chain parameters at runtime:

Set chain ID

    $ cast rpc anvil_setChainId 31337

Set block gas limit

    $ cast rpc evm_setBlockGasLimit 0x1C9C380

Set next block base fee

    $ cast rpc anvil_setNextBlockBaseFeePerGas 0x5F5E100

### Transaction pool[](https://www.getfoundry.sh/anvil/custom-methods#transaction-pool)

Inspect and manage pending transactions:

Get pending transactions

    $ cast rpc txpool_content

Drop a transaction

    $ cast rpc anvil_dropTransaction $TX_HASH

Drop all pending transactions

    $ cast rpc anvil_dropAllTransactions

### Tracing[](https://www.getfoundry.sh/anvil/custom-methods#tracing)

Enable execution traces for debugging:

Enable trace printing

    $ anvil --print-traces

Enable step tracing for debug\_\* methods

    $ anvil --steps-tracing

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