crpc 0.9.4

Chain-aware RPC CLI — auto ABI encode/decode, 2600+ chains, Etherscan V2, batch Multicall3, and more
crpc-0.9.4 is not a library.

crpc

Chain-aware RPC CLI — cast but better.

Auto ABI encode/decode, 2600+ chains via chainlist.org, Etherscan V2 integration with RPC fallback, built-in token registry, batch Multicall3, event logs with block range shortcuts, trace, bytecode inspection, and formatted output.

Install

cargo install --path .

Commands

Command Description
call eth_call with auto ABI encode/decode
balance ERC-20 token balance query
allowance ERC-20 allowance check
abi Fetch contract ABI from Etherscan (--raw for JSON)
verify Batch verify contract addresses (code on-chain)
pools Discover pools from factory contract events
code Get contract bytecode size/existence
slot Read contract storage slot
block Get block info
tx Transaction details + receipt + decoded logs
logs Query and decode event logs
trace Debug trace a transaction (requires archive node)
multi Batch calls via Multicall3
diff Compare on-chain values across blocks
gas Current gas prices (Etherscan + RPC fallback)
history Transaction history (Etherscan + RPC fallback)
transfers ERC-20 token transfer history
chains List or search 2600+ chains from chainlist.org
encode ABI-encode a function call (offline)
decode ABI-decode hex data (offline)
config Manage persistent configuration (set/get)

Global flags

--rpc <URL>            Override RPC URL (highest priority)
--provider <NAME>      Select named provider from config
--json                 Output as JSON

Usage

crpc call — eth_call with auto decode

crpc call base 0x4200000000000000000000000000000000000006 "name()(string)"
# [0] string = Wrapped Ether

crpc call base 0x4200000000000000000000000000000000000006 "decimals()(uint8)"
# [0] uint8 = 18

# Negative int arg
crpc call base 0xABCD...pool "getTick(int32)(int24)" -- -30

# Raw hex output
crpc call base 0xABCD...pool "getState()(uint256,int24,uint256)" --raw

# Historical query at specific block
crpc call eth 0x... "balanceOf(address)(uint256)" 0x... --block 19000000

crpc balance — ERC-20 balance

crpc balance base WETH 0xYourAddress
# Balance: 871000000000000000
# Human: 0.871 WETH

# Token address directly
crpc balance arb 0xaf88d065e77c8cC2239327C5EDb3A432268e5831 0xYourAddress

crpc allowance — ERC-20 allowance check

crpc allowance base USDC 0xOwner 0xSpender
# Token:     USDC
# Owner:     0xOwner
# Spender:   0xSpender
# Allowance: unlimited (max uint256)

# With token address
crpc allowance arb 0xaf88d065e77c8cC2239327C5EDb3A432268e5831 0xOwner 0xSpender

crpc code — Contract bytecode check

crpc code base 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913
# Address: 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913
# Type:    Contract
# Size:    1852 bytes
# Code:    0x60806040...060c0033

crpc code eth 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045
# Type:    EOA (no bytecode)

Useful for verifying if an address is a contract or EOA during DEX investigation.

crpc abi — Fetch contract ABI

crpc abi eth 0xdAC17F958D2ee523a2206206994597C13D831ec7
# transfer(address,uint256) -> (bool)
# approve(address,uint256) -> (bool)
# event Transfer(address indexed,address indexed,uint256)
# ...

# Raw JSON ABI output
crpc abi eth 0xdAC17F958D2ee523a2206206994597C13D831ec7 --raw
# [{ "type": "function", "name": "transfer", ... }]

# Also works with --json global flag
crpc --json abi eth 0xdAC17F958D2ee523a2206206994597C13D831ec7

Requires ETHERSCAN_API_KEY (via env var or crpc config set).

crpc verify — Batch verify addresses

crpc verify eth 0xdAC17F958D2ee523a2206206994597C13D831ec7 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045
# Address                                    Status    Size
# 0xdAC17F958D2ee523a2206206994597C13D831ec7 CONTRACT  10.8 KB
# 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045 EOA       -

crpc verify eth 0xAddress1 0xAddress2 --json
# [{"address":"0x...","is_contract":true,"code_size":11075}, ...]

crpc pools — Discover pools from factory events

# Uniswap V2 factory (default: PairCreated event)
crpc pools eth 0x5C69bEe701ef814a2B6a3EDD4B1652CB9cc5aA6f --limit 5
# Pool                                       Token0                                     Token1
# 0xDe05cb...b744                            0xC02aaA...6Cc2 (WETH)                     0xF385fc...049a

# Uniswap V3 factory with custom event
crpc pools eth 0x1F98431c8aD98523631AE4a59f267346ea31F984 \
  --event "PoolCreated(address indexed,address indexed,uint24,int24,address)" \
  --from 12369621 --limit 10

# JSON output
crpc pools eth 0x5C69bEe701ef814a2B6a3EDD4B1652CB9cc5aA6f --json --limit 3

crpc slot — Storage slot read

crpc slot base 0x4200000000000000000000000000000000000006 0
# Slot 0: 0x577261707065642045746865720000000000000000000000000000000000001a
# As uint256: 3955331089...

crpc block — Block info

crpc block base
# Number: 43432032
# Hash: 0xe5a982...
# Timestamp: 1773653411
# Gas used: 51663520
# Transactions: 190

crpc block eth 19000000

crpc tx — Transaction + receipt

crpc tx base 0xTxHash
# From: 0x...
# To: 0x...
# Value: 0
# Status: true
# Gas used: 21000
# Log count: 3

crpc logs — Query event logs

# Last 1000 blocks from a contract (no --from/--to needed)
crpc logs base 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 --blocks 1000

# Filter and decode Transfer events
crpc logs eth 0xdAC17F958D2ee523a2206206994597C13D831ec7 \
  --event "Transfer(address indexed,address indexed,uint256)" \
  --blocks 100 --limit 10

# Filter by raw topic0 hash (for unknown/custom events)
crpc logs base 0xPoolAddress \
  --topic0 0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef \
  --blocks 500

# Explicit block range
crpc logs eth 0xAddress --from 19000000 --to 19000100

crpc trace — Debug trace a transaction

crpc trace eth 0xTxHash
# CALL 0xFrom -> 0xTo  value: 0
#   STATICCALL 0xTo -> 0xContract1
#     output: 0x... (32 bytes)

crpc trace eth 0xTxHash --depth 3

Requires an archive/debug node (Alchemy, QuickNode, etc).

crpc diff — Compare values across blocks

crpc diff base 0xPool "slot0()(uint160,int24,uint16)" --from 43000000 --to 43001000

crpc gas — Gas price oracle

crpc gas eth
# Gas Prices (Gwei):
#   Safe:     20
#   Standard: 25
#   Fast:     30
#   Base fee: 18.5

# Works on L2s too — falls back to RPC when Etherscan unavailable
crpc gas base
# Gas Price (via RPC):
#   Gas price: 0.006 Gwei
#   Priority:  0.001 Gwei

Uses Etherscan gas oracle when available, falls back to eth_gasPrice / eth_maxPriorityFeePerGas RPC calls on chains where Etherscan requires a paid plan (Base, Arbitrum, etc).

crpc history — Transaction history

crpc history eth 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045 --limit 5

# Works on L2s — falls back to recent block scanning via RPC
crpc history base 0xAddress --limit 10

Uses Etherscan when available, falls back to scanning recent blocks via RPC.

crpc transfers — Token transfer history

# All ERC-20 transfers
crpc transfers eth 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045

# Filter by token contract
crpc transfers eth 0xAddress --token 0xdAC17F958D2ee523a2206206994597C13D831ec7

Requires ETHERSCAN_API_KEY.

crpc chains — Browse 2600+ chains

crpc chains              # Top 30 by RPC availability
crpc chains fantom       # Search by name
crpc chains 250          # Search by chain ID

Any chain from chainlist.org works automatically — no config needed:

crpc block fantom          # Fantom Opera (chain 250)
crpc block gnosis          # Gnosis Chain (chain 100)
crpc block moonbeam        # Moonbeam (chain 1284)
crpc block 250             # By chain ID directly

crpc encode / crpc decode — Offline ABI tools

crpc encode "transfer(address,uint256)" 0xRecipient 1000000
# 0xa9059cbb000000000000000000000000...00000000000000000000000000000f4240

# Decode with function signature — typed output
crpc decode "swap(address,bool,int256,uint160)" 0x04e45aaf000000...
# [0] address = 0x833589fcd6edb6e08f4c7c32d4f71b54bda02913
# [1] bool = true
# [2] int256 = 100
# [3] uint160 = 200

# Decode raw tuple
crpc decode "(uint256,address)" 0x000000...

crpc multi — Batch calls via Multicall3

crpc multi base calls.json

calls.json:

[
  {"target": "0x4200..0006", "sig": "name()(string)", "args": []},
  {"target": "0x4200..0006", "sig": "decimals()(uint8)", "args": []},
  {"target": "0x8335..2913", "sig": "symbol()(string)", "args": []}
]

All calls execute in a single RPC request.

Chain Support

Built-in aliases

Alias Chain ID
eth / ethereum 1
base 8453
arb / arbitrum 42161
bsc 56
polygon / matic 137
op / optimism 10
avax / avalanche 43114
linea 59144
scroll 534352
zksync / zksync-era 324

You can use chain IDs directly: crpc block 8453.

Beyond built-in chains, crpc supports 2600+ chains via chainlist.org. Run crpc chains to browse.

Built-in tokens

Chain Tokens
eth WETH, USDC, USDT, DAI, WBTC
base WETH, USDC, USDbC, cbETH
arb WETH, USDC, USDC.e, USDT, WBTC, ARB

Etherscan Integration

Commands abi, gas, history, and transfers use the Etherscan V2 API — a single unified endpoint supporting 60+ chains. On L2 chains where Etherscan requires a paid plan, gas and history automatically fall back to RPC methods.

# Option 1: persistent config (recommended)
crpc config set etherscan_api_key your_key_here

# Option 2: environment variable
export ETHERSCAN_API_KEY=your_key_here  # free at etherscan.io/apis

JSON Output

All commands support --json for machine-readable output:

crpc --json call base 0x... "name()(string)"
crpc --json block eth 19000000
crpc --json gas eth
crpc --json code base 0x...

RPC Provider Selection

Resolution priority

  1. --rpc <url> flag — use directly
  2. CRPC_{CHAIN}_RPC env var (e.g. CRPC_ETH_RPC=https://...)
  3. --provider <name> flag — named provider from config
  4. default_provider from config file
  5. priority list — first provider whose env vars resolve
  6. Chainlist.org public RPCs
  7. Built-in fallback RPCs

When a chain has multiple providers, crpc automatically tries the next on transport errors (timeout, connection refused). Contract-level errors (reverts) do not trigger fallback.

crpc config — Manage persistent configuration

crpc config set etherscan_api_key YOUR_KEY
crpc config set default_provider alchemy

crpc config get etherscan_api_key
# YOUR_KEY

Settings are stored in ~/.crpc.toml. Environment variables override config values.

Configuration

~/.crpc.toml:

default_provider = "alchemy"

[chains.eth]
chain_id = 1
priority = ["alchemy", "llamarpc"]

[chains.eth.rpc]
alchemy = "https://eth-mainnet.g.alchemy.com/v2/${ALCHEMY_API_KEY}"
llamarpc = "https://eth.llamarpc.com"

[chains.base]
chain_id = 8453
priority = ["alchemy", "base"]

[chains.base.rpc]
alchemy = "https://base-mainnet.g.alchemy.com/v2/${ALCHEMY_API_KEY}"
base = "https://mainnet.base.org"

[tokens.base]
DEGEN = "0x4ed4E862860beD51a9570b96d89aF5E1B0Efefed"

URLs support ${VAR_NAME} environment variable expansion. Providers with unresolvable variables are automatically skipped.

Function Signature Format

functionName(paramTypes)(returnTypes)

Examples: balanceOf(address)(uint256), name()(string), transfer(address,uint256)(bool)

Return types are optional — omit for raw hex word output.