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Foundry is a fast and modular toolkit for Ethereum application development written in Rust. It provides four main command-line tools—forge, cast, anvil, and chisel—to streamline everything from project setup to live-chain interactions. Among these, cast serves as your “Swiss-army knife” for JSON-RPC calls, letting you execute tedious day-to-day tasks (like sending raw transactions, querying balances, fetching blocks, and looking up chain metadata) with simple, consistent commands instead of verbose curl scripts. This guide walks you through installing Foundry, configuring your environment, and using the most common cast commands to accelerate your development workflow.

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Installation & Setup

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Install Foundry

Run the following command to install foundryup, the Foundry toolchain installer. This will give you the four main binaries. 
curl -L https://foundry.paradigm.xyz | bash
foundryup
After installation, you can switch to the nightly builds for the latest features, though this is optional. 
foundryup -i nightly

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Verify Installation

Check that each binary was installed correctly by running: 
foundryup --version
cast --version
forge --version
anvil --version
You should see version outputs for each tool (e.g., cast 0.2.0).

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Configuration

To avoid passing the --rpc-url flag with every command, you can set defaults in a foundry.toml file. This file can be placed in your project’s root directory for project-specific settings, or you can create a global configuration at ~/.foundry/foundry.toml for settings you use across all projects. Here is an example of a global configuration for connecting to a local Cosmos EVM node:
~/.foundry/foundry.toml
# ~/.foundry/foundry.toml

# Declare your named endpoints (optional; for forge test / forking)
[rpc_endpoints]
cosmos = "<evm_rpc_url>"

# Configure the default profile for cast/forge/anvil
[profile.default]
# Tell Foundry which chain you're targeting:
chain_id     = 4321
# Directly tell cast to use your endpoint:
eth_rpc_url  = "<evm_rpc_url>"
# Set EVM version for Solidity compilation
evm_version  = "istanbul"
With this global configuration, Foundry tools will automatically connect to your local node without needing additional flags.

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Basic Usage of cast

cast replaces the need for custom shell scripts and verbose curl commands by offering first-class RPC commands.

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Chain Metadata

  • Get Chain ID 
    cast chain-id --rpc-url local
    Returns the chain ID in decimal format.
  • Get Client Version 
    cast client --rpc-url local
    Displays the client implementation and version (e.g., reth/v1.0.0).

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cast Command Reference

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Chain Commands

CommandPurpose
cast chainShow the symbolic name of the current chain.
cast chain-idFetch the numeric chain ID.
cast clientGet the JSON-RPC client version.
Example: 
# Assuming FOUNDRY_RPC_URL is set or using a configured alias
cast chain
cast chain-id
cast client

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Transaction Commands

CommandPurpose
cast sendSign and publish a transaction.
cast publishPublish a raw, signed transaction.
cast receiptFetch the receipt for a transaction hash.
cast txQuery transaction details (status, logs, etc.).
cast rpcInvoke any raw JSON-RPC method.
  • Sign and Send (using a private key or local keystore): 
    cast send 0xRecipientAddress "transfer(address,uint256)" "0xSomeOtherAddress,100" --private-key $YOUR_PK
  • Publish Raw Transaction (hex-encoded): 
    cast publish 0xf86b808504a817c80082520894...
  • Generic RPC Call: 
    cast rpc eth_sendRawTransaction 0xf86b8085...

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Account & Block Commands

CommandPurpose
cast balanceGet an account’s balance (supports ENS and units).
cast blockFetch block information by number or hash.
cast block-numberGet the latest block number.
cast logsQuery event logs.
  • Get Balance (with unit flag): 
    # Using an ENS name on Ethereum mainnet
cast balance vitalik.eth --ether --rpc-url https://eth.merkle.io
  • Get Block Details: 
    cast block latest

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Utility & Conversion Commands

CommandPurpose
cast estimateEstimate gas for a call or deployment.
cast find-blockFind a block by its timestamp.
cast compute-addressCalculate a CREATE2 address.
cast from-binDecode binary data to hex.
cast from-weiConvert wei to a more readable unit (e.g., ether).
cast to-weiConvert a unit (e.g., ether) to wei.
cast abi-encodeEncode function arguments.
cast keccakHash data with Keccak-256.
These commands allow you to drop one-off scripts for common conversions and estimations.

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Streamlining Repetative / Tedious tasks

When performing testing or development roles you may find yourself doing one or more small but very tedious tasks frequently. In your shell’s configuration file (~/.bashrc, ~/.zshrc), you can alias cast with your default RPC URL (or multiple on various chains) to save time. 
# Set your default RPC endpoint
export CDEV_RPC="<evm_rpc_url>"
# Create an alias
alias ccast='cast --rpc-url $CDEV_RPC'

# Now you can run commands like:
ccast balance 0x...
This is an extremely basic example of how you can improve your workflows by building upon the heavy lifting Foundry already does out of the box.