# Web3 Tools

Check and decode crypto addresses, hashes, selectors and units without a node.

## How to pay

Machine-payable over x402. USDC on: Base (eip155:8453), Solana (solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp), Polygon (eip155:137), Arbitrum One (eip155:42161).
No accounts. No API keys. No signup. The paying wallet is the account.

## Machine-readable

- OpenAPI: https://web3-tools.x402tookit.com/openapi.json
- x402 manifest: https://web3-tools.x402tookit.com/.well-known/x402
- Catalog (free): https://web3-tools.x402tookit.com/catalog
- Health (free): https://web3-tools.x402tookit.com/health
- Uptime (free): https://web3-tools.x402tookit.com/uptime

## Endpoints (12)

### GET /btc-address — $0.02
Validate a Bitcoin address (legacy, P2SH, SegWit bech32, Taproot bech32m): checksum, type, network and hash payload.
Params: address: string
Example: https://web3-tools.x402tookit.com/btc-address?address=bc1qw508d6qejxtdg4y5r3zarvary0c5xw7kv8f3t4

### GET /caip-parse — $0.02
Parse CAIP-2 chain ids, CAIP-10 account ids and CAIP-19 asset ids: namespace, reference, known chain name, address check.
Params: id: string
Example: https://web3-tools.x402tookit.com/caip-parse?id=eip155%3A8453

### GET /calldata-split — $0.02
Split EVM calldata into its 4-byte selector and 32-byte words, naming common ERC-20/721 calls and spotting addresses.
Params: data: string
Example: https://web3-tools.x402tookit.com/calldata-split?data=0xa9059cbb000000000000000000000000ab5801a7d398351b8be11c439e05c5b3259aec9b0000000000000000000000000000000000000000000000000de0b6b3a7640000

### GET /contract-address — $0.02
Predict a contract address: CREATE from deployer and nonce, or CREATE2 from deployer, salt and init code (or its hash).
Params: deployer: string, nonce?: string, salt?: string, initCode?: string, initCodeHash?: string
Example: https://web3-tools.x402tookit.com/contract-address?deployer=0x6ac7ea33f8831ea9dcc53393aaa88b25a785dbf0&nonce=0

### GET /ens-namehash — $0.02
Compute the ENS namehash (EIP-137) and label hashes for a name such as vitalik.eth, for contract calls and subgraph queries.
Params: name: string
Example: https://web3-tools.x402tookit.com/ens-namehash?name=foo.eth

### GET /evm-address — $0.02
Check an EVM address (Ethereum, Base, Polygon...) against its EIP-55 checksum and return the correctly checksummed form.
Params: address: string
Example: https://web3-tools.x402tookit.com/evm-address?address=0x5aAeb6053F3E94C9b9A09f33669435E7Ef1BeAed

### GET /function-selector — $0.02
Compute the 4-byte function selector and event topic0 from a Solidity signature such as transfer(address,uint256).
Params: signature: string
Example: https://web3-tools.x402tookit.com/function-selector?signature=transfer%28address%2Cuint256%29

### GET /hex-convert — $0.02
Convert hex to UTF-8 text or an integer (signed or unsigned), and text or integers to hex with 32-byte padding.
Params: op: string, value: string
Example: https://web3-tools.x402tookit.com/hex-convert?op=hex-to-int&value=0x0de0b6b3a7640000

### GET /keccak256 — $0.02
Keccak-256 hash (the Ethereum one) of text or hex bytes, with the first-4-byte selector and NIST SHA3-256 for contrast.
Params: input: string, encoding?: string
Example: https://web3-tools.x402tookit.com/keccak256?input=transfer%28address%2Cuint256%29&encoding=utf8

### GET /solana-address — $0.02
Validate a Solana address: base58, 32 bytes, and whether it is on the ed25519 curve (wallet) or off it (program-derived).
Params: address: string
Example: https://web3-tools.x402tookit.com/solana-address?address=EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v

### GET /tx-hash-check — $0.02
Recognise what a transaction id looks like (EVM hash, Bitcoin txid, Solana signature) from format alone, and flag typos.
Params: id: string
Example: https://web3-tools.x402tookit.com/tx-hash-check?id=0x88df016429689c079f3b2f6ad39fa052532c56795b733da78a91ebe6a713944b

### GET /unit-convert — $0.02
Exact unit conversion for crypto amounts: wei, gwei, ether, lamports, SOL, satoshis, BTC or a token with N decimals.
Params: amount: string, unit: string, decimals?: integer
Example: https://web3-tools.x402tookit.com/unit-convert?amount=1.5&unit=ether

## Terms

Computed locally from public specifications. A well-formed address or valid checksum does not mean the address exists, is funded, or belongs to anyone; nothing here sends a transaction, holds keys or gives financial advice.