Name, symbol, decimals and total supply of any ERC20 contract in one call. Useful to label a token address before showing it to a user. Via eth_call. Pay per call in USDC over x402: no API key, no account, no signup. Answers both GET and POST. Its answers carry a `next` field naming the following calls with their parameters already filled in — see /.well-known/skills/.

Next transaction nonce for any address, and whether the address is a contract. What an agent needs before signing a transaction. Via eth_getTransactionCount. Pay per call in USDC over x402: no API key, no account, no signup. Answers both GET and POST. Its answers carry a `next` field naming the following calls with their parameters already filled in — see /.well-known/skills/.

Resolves an ENS name to its address, or an address back to its primary ENS name, reading Ethereum mainnet directly. Names are what humans paste and addresses are what chains need. Pay per call in USDC over x402: no API key, no account, no signup. Answers both GET and POST. Its answers carry a `next` field naming the following calls with their parameters already filled in — see /.well-known/skills/.

Current gas price and base fee for any supported chain, in wei and gwei, plus the cost estimate of a plain transfer. For agents planning a transaction. Via eth_gasPrice. Pay per call in USDC over x402: no API key, no account, no signup. Answers both GET and POST. Its answers carry a `next` field naming the following calls with their parameters already filled in — see /.well-known/skills/.

Live health of every supported chain in one call: chain id, block height and how stale the head is. Use it to pick a chain that is actually responding. Via eth_getBlockByNumber. Pay per call in USDC over x402: no API key, no account, no signup. Answers both GET and POST. Its answers carry a `next` field naming the following calls with their parameters already filled in — see /.well-known/skills/.

Tells whether an address is a smart contract or a plain wallet, and how big its bytecode is. A cheap safety check before sending funds. Via eth_getCode. Pay per call in USDC over x402: no API key, no account, no signup. Answers both GET and POST. Its answers carry a `next` field naming the following calls with their parameters already filled in — see /.well-known/skills/.

Full transaction details by hash, merged with its receipt: from, to, value, gas used, status and block. One call instead of two. Via eth_getTransactionByHash. Pay per call in USDC over x402: no API key, no account, no signup. Answers both GET and POST. Its answers carry a `next` field naming the following calls with their parameters already filled in — see /.well-known/skills/.

Spot price of any ERC20 read straight from the deepest Uniswap V3 pool against USDC, on Base, Ethereum, Polygon, Arbitrum or Optimism. Returns the pool address, fee tier, liquidity, sqrtPriceX96, tick and block, so the number can be audited instead of trusted. No aggregator and no API key: the source is the chain itself. Via eth_call. Pay per call in USDC over x402: no API key, no account, no signup. Answers both GET and POST. Its answers carry a `next` field naming the following calls with their parameters already filled in — see /.well-known/skills/.

How much of a token a spender is still allowed to move on an owner's behalf, and whether that approval is unlimited. The check to run before an approve, and the one that finds forgotten infinite approvals. Via eth_call (allowance). Pay per call in USDC over x402: no API key, no account, no signup. Answers both GET and POST. Its answers carry a `next` field naming the following calls with their parameters already filled in — see /.well-known/skills/.

Receipt of a transaction: whether it succeeded or reverted, gas used, fee actually paid, and how many logs it emitted. The call that answers did my transaction work. Via eth_getTransactionReceipt. Pay per call in USDC over x402: no API key, no account, no signup. Answers both GET and POST. Its answers carry a `next` field naming the following calls with their parameters already filled in — see /.well-known/skills/.

Runs any read-only contract call (eth_call) with your own calldata and returns the raw result, on five chains, with no API key and no rate limit. The escape hatch for anything the typed endpoints do not cover. Pay per call in USDC over x402: no API key, no account, no signup. Answers both GET and POST. Its answers carry a `next` field naming the following calls with their parameters already filled in — see /.well-known/skills/.

Reads a raw storage slot of any contract, decoded as hex, integer and address. How you inspect proxy implementation slots, owners and paused flags that have no public getter. Via eth_getStorageAt. Pay per call in USDC over x402: no API key, no account, no signup. Answers both GET and POST. Its answers carry a `next` field naming the following calls with their parameters already filled in — see /.well-known/skills/.

Cumulative XRP/RLUSD order-book depth by basis-point band, and the execution-cost curve (VWAP slippage) for order sizes from 10 to 100,000 XRP, measured first-party from the XRP Ledger. Answers 'how much can I move and what will it cost' rather than publishing a price. Depth counts funded amounts only - unfunded offers are excluded as phantom liquidity that cannot fill. Also serves the XRPL x402 agentic-payment market reconstructed from the public ledger. Descriptive market data, lagged at least 5 minutes; not a low-latency trading feed.

Read-only Bitcoin and Ethereum mainnet RPC for AI agents: seven Bitcoin methods and 37 Ethereum methods covering balances, blocks, transactions, receipts, logs, proofs and simulations. One POST endpoint per network; JSON-RPC method and params in the body. Payments currently use test USDC on Base Sepolia through Coinbase CDP, at 0.0025–0.01 per call. Historical Ethereum state is subject to node retention; archive state is not guaranteed. HTTP RPC: POST https://api.block402.xyz/rpc/bitcoin or POST https://api.block402.xyz/rpc/ethereum. Method-specific URLs are no longer supported. Documentation: https://api.block402.xyz/openapi.json. Contact: [email protected]. Bitcoin quote example (do not pay a discovery-only challenge): KEY=$(openssl rand -hex 32) curl --include https://api.block402.xyz/rpc/bitcoin -H 'Content-Type: application/json' -H "Idempotency-Key: $KEY" -d '{"jsonrpc":"2.0","id":1,"method":"getblockcount","params":[]}' Persist the private key before payment; reuse it only for recovery of this same request. Sign the returned bound x402 quote and retry with PAYMENT-SIGNATURE. The same /rpc/bitcoin URL serves all seven supported methods.

ERC20 token balance for any wallet - USDC, USDT, DAI or any token - via balanceOf. Returns the raw amount and the decimals so you can format it. Via eth_call (balanceOf). Pay per call in USDC over x402: no API key, no account, no signup. Answers both GET and POST. Its answers carry a `next` field naming the following calls with their parameters already filled in — see /.well-known/skills/.

Latest block height and timestamp of any supported chain, plus how old the chain head is in seconds. Tells an agent whether a node is in sync. Via eth_getBlockByNumber. Pay per call in USDC over x402: no API key, no account, no signup. Answers both GET and POST. Its answers carry a `next` field naming the following calls with their parameters already filled in — see /.well-known/skills/.

Estimates the gas a transaction would need and prices it at the current gas price, before you sign anything. Also the cheapest way to find out that a call would revert. Via eth_estimateGas. Pay per call in USDC over x402: no API key, no account, no signup. Answers both GET and POST. Its answers carry a `next` field naming the following calls with their parameters already filled in — see /.well-known/skills/.

Who owns a given ERC721 token id, plus its tokenURI and collection name in the same call. Answers is this NFT still theirs without an indexer or an API key. Via eth_call (ownerOf). Pay per call in USDC over x402: no API key, no account, no signup. Answers both GET and POST. Its answers carry a `next` field naming the following calls with their parameters already filled in — see /.well-known/skills/.