OneSource - Pay-per-call Ethereum RPC for Agents — MPP Grade B

Returns how much of an ERC20 token a spender is approved to transfer from an owner via eth_call on allowance(owner, spender). Use before calling transferFrom, or to audit outstanding approvals for security review.

Returns the latest mined Ethereum block height via eth_blockNumber against a live node. No caching - every call queries the upstream RPC fresh. Use this to sync an agent to the chain tip, to detect progress or stalls, or as a cheap liveness ping before issuing more expensive RPC calls.

Returns the block header plus its transaction hashes for a given block number, tag (latest, pending, safe, finalized), or hex block number via eth_getBlockByNumber. Live from the upstream RPC node.

Simulates a contract read via eth_call - returns the raw ABI-encoded result without submitting a transaction. Pass 'to' (contract address) and 'data' (ABI-encoded calldata); optional 'from', 'value', and 'block' override the caller, msg.value, and block tag.

Returns the EIP-155 chain ID via eth_chainId, queried live from the upstream RPC node. Verify a backend is serving the expected chain before signing an EIP-155 transaction.

Returns the deployed bytecode at an address via eth_getCode. Empty bytecode means the address is an EOA (wallet); non-empty means it's a contract. Response includes a bytecode_size field for quick classification.

Introspects a contract via eth_call - probes name(), symbol(), decimals(), and supportsInterface() to report what token standards (ERC20, ERC721, ERC1155) the contract claims to implement. Ideal for classifying an unknown contract.

Resolves a *.eth ENS name to its address (forward lookup) or an address to its primary ENS name (reverse lookup) via eth_call on the ENS Registry and Resolver contracts. Auto-detects direction from the input format.

Fetches an account's balance of a specific ERC1155 token_id by eth_call-ing balanceOf(address, uint256). Supports any ERC1155 contract - gaming items, editions, semi-fungible assets.

Fetches an account's balance of a specific ERC20 token by eth_call-ing balanceOf(address). Returns the raw balance plus the token's decimals and symbol for convenience. Works for any ERC20 contract.

Specialized eth_getLogs query that filters on the ERC20 Transfer(address,address,uint256) topic and optionally narrows to a token contract or a specific wallet (sender or recipient). Decodes the indexed from/to and raw value.

Lists every ERC721 token_id held by an owner by combining balanceOf(owner) with tokenOfOwnerByIndex(owner, i) across a batched set of eth_call requests. Requires the contract to implement the ERC721Enumerable extension.

Estimates the gas a transaction would consume via eth_estimateGas. Accepts the same 'to', 'data', 'from', 'value' fields as /call. A failing estimate usually means the transaction would revert - use this to pre-flight a complex interaction before paying gas.

Queries contract event logs via eth_getLogs with optional filters on contract address, topic0 (event signature hash), and block range. Returns the raw logs - address, topics, data, block_number, tx_hash.

Fetches the wallet's native ETH balance (eth_getBalance) and, when you pass a comma-separated list of ERC20 contract addresses in the optional 'tokens' param, batches a balanceOf eth_call per token alongside symbol() and decimals(). Returns a single snapshot of ETH plus any requested token balances. Live from the upstream RPC node.

Batches eth_chainId, eth_blockNumber, and eth_gasPrice into a single round-trip to the upstream RPC node. Use this instead of three separate calls when bootstrapping an agent, probing liveness, or pre-flighting a transaction.

Calls tokenURI(tokenId) (ERC721) or uri(tokenId) (ERC1155) via eth_call, resolves ipfs:// URIs through a gateway, and returns the resolved metadata JSON alongside the raw URI. Works for most compliant NFT contracts.

Returns the current owner of a specific ERC721 NFT via eth_call on ownerOf(tokenId). Reverts for unminted or burned token IDs - the error surfaces as an RPC error.

Returns the number of transactions sent from this address via eth_getTransactionCount. Pass block="pending" (default) for the next-nonce an EIP-1559 or legacy transaction should use, or a confirmed tag for historical nonces. Use this to build a correctly-nonced transaction or to diagnose stuck transactions.

Returns the pending block as seen by the upstream RPC node - transactions that are in the mempool but not yet included on-chain, via eth_getBlockByNumber("pending"). Use this to monitor unconfirmed activity, spot front-running risk, or peek at what a node plans to mine next.

Reads well-known proxy storage slots via eth_getStorageAt to detect EIP-1967, UUPS, and Transparent proxy patterns, and returns the current implementation address. Also surfaces the admin slot when present.

Returns the mined transaction receipt - status (success/failed), gas used, effective gas price, emitted event logs, and block inclusion data - via eth_getTransactionReceipt. Returns null if the transaction is pending or unknown to the node.

Reads a 32-byte storage slot directly from a contract's storage via eth_getStorageAt. Useful for inspecting EIP-1967 proxy implementation slots, packed variables, and storage layouts that aren't exposed through a public function.

Returns the total supply of a token contract via eth_call on totalSupply(). Works for ERC20 (raw token units) and ERC721 (count of minted NFTs) contracts that implement the standard.

Returns the full transaction object - from, to, value, gas, nonce, calldata, block inclusion - via eth_getTransactionByHash. Returns null if the transaction is pending eviction or unknown to the node.