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x402 research echo · x402-echo-service.onrender.com
Echo service for x402 protocol research. POST a JSON body with a "message" string; the response returns the message, its SHA-256 digest and a server timestamp. Payment is live: $0.001 USDC on Base is verified and settled via the Coinbase CDP facilitator, so callers ARE charged. The response is computed before settlement, and the settlement tx hash is returned in the body and in PAYMENT-RESPONSE.
https://x402-echo-service.onrender.com/base64
Encode or decode base64. POST {"mode":"encode","input":"..."} or {"mode":"decode",...}. Supports standard and url-safe alphabets via {"urlsafe":true}. Decoding validates the input and reports an error rather than returning silent garbage.
https://x402-echo-service.onrender.com/chain/block
Read the head of the Base chain, or a specific block. POST {} for the latest block, or {"number":12345678} for one by height. Returns number, hash, unix timestamp, gas used and transaction count. Useful as an authoritative chain clock.
https://x402-echo-service.onrender.com/chain/code
Determine whether an address on Base is a contract or an externally owned account. POST {"address":"0x..."} and receive isContract, the bytecode size in bytes and its keccak-256 hash. Useful before sending funds to an unfamiliar address.
https://x402-echo-service.onrender.com/chain/erc20-balance
Read an ERC-20 token balance on Base. POST {"address":"0x...","token":"0x..."} and receive the raw balance, the token decimals and the human-readable amount. Defaults to USDC when token is omitted. Live chain state, no indexer lag.
https://x402-echo-service.onrender.com/chain/eth-balance
Read the native ETH balance of an address on Base. POST {"address":"0x..."} and receive the balance in wei and in ether. Live chain state read directly from a node, with no indexer lag and no API key.
https://x402-echo-service.onrender.com/chain/gas
Current gas conditions on Base. POST {} and receive the legacy gas price and the EIP-1559 base fee of the latest block, in wei and gwei. Useful for agents deciding whether to transact now or wait.
https://x402-echo-service.onrender.com/chain/nonce
Read the transaction count of an address on Base. POST {"address":"0x..."} with an optional {"pending":true} to include the mempool. Returns the nonce an agent should use for its next transaction.
https://x402-echo-service.onrender.com/chain/token
Read ERC-20 metadata on Base. POST {"token":"0x..."} and receive the name, symbol, decimals and total supply, with the supply given both raw and decimal-adjusted. Reports a clear error when the address is not a token contract.
https://x402-echo-service.onrender.com/chain/tx
Look up a transaction on Base by hash. POST {"hash":"0x..."} and receive its status, block number, from and to addresses, value, gas used and effective gas price. Returns a clear not-found rather than an empty object when the hash is unknown.
https://x402-echo-service.onrender.com/echo
Echo service for x402 protocol research. POST a JSON body with a "message" string; the response returns the message, its SHA-256 digest and a server timestamp. Payment is live: $0.001 USDC on Base is verified and settled via the Coinbase CDP facilitator, so callers ARE charged. The response is computed before settlement, and the settlement tx hash is returned in the body and in PAYMENT-RESPONSE.
https://x402-echo-service.onrender.com/hash
Compute cryptographic digests of a string. POST {"input":"...","algorithms":["sha256"]} and receive one hex digest per requested algorithm. Supports sha256, sha512 and keccak256. Deterministic, no storage, no upstream calls.
https://x402-echo-service.onrender.com/time
Server time in several formats at once. POST {} and receive the current UTC instant as ISO-8601, unix seconds, unix milliseconds and RFC-2822. Useful for agents that need an authoritative clock they did not compute themselves.
https://x402-echo-service.onrender.com/uuid
Generate cryptographically random UUIDv4 identifiers. POST {"count":10} and receive that many unique v4 UUIDs, 1 to 100 per call. Uses the platform CSPRNG. No storage.
https://x402-echo-service.onrender.com/web/search
Web search for agents. POST a JSON body with a "query" string and an optional "limit" (1-20); returns ranked results, each with a title, url and text snippet. Keyword and semantic matching, no API key required, billed per call: $0.001000 USDC.
This listing is taken from the catalogues and the provider named above. The price is what that source advertised.
