x402 on-chain audits

Endpoints (22 live)

• GET /selector — Offline ABI selector generator (chain-agnostic, no RPC): human function signature in (transfer(address,uint256), optional parameter names, arrays address[], tuples (bytes,address,uint256,uint256)) and the 4-byte selector out, with full keccak256, parsed inputs and a round-trip verification against the /decode dictionary (verify.known); kind=event switches to the 32-byte topic0 (Transfer/Approval/Swap/Sync/Paused...). Pure cryptography: no RPC, no explorer, no API key, instant response, 100% margin (0.1 USDC on Base)
• GET /balance — Wallet balance on Base, Optimism or Ethereum Mainnet: native ETH or any ERC-20 balance for any address, with decimals, formatted value and block number (no explorer API) (0.1 USDC on Base)
• GET /tx — Transaction status on Base: on-chain receipt for any tx hash — success/reverted, block number, gas used, from/to, value and log count (no explorer API) (0.1 USDC on Base)
• GET /token — Token safety audit on Base: honeypot simulation, buy/sell/transfer taxes, liquidity USD, holders, source verification, proxy, owner renouncement — 0-100 score + verdict (0.25 USDC on Base)
• GET /abi — Offline ABI map generator (chain-agnostic, no RPC): a contract ABI (JSON array of entries) in, the full selector map out — 4-byte selector + canonical signature + typed inputs/outputs for every function, 32-byte topic0 for every event (indexed/anonymous flags) and 4-byte selector for every error, with a round-trip verification against the /decode dictionary (verify.known — which functions/events this API can already decode/encode). Pure cryptography: no RPC, no explorer, no API key, instant response, 100% margin (0.1 USDC on Base)
• GET /eip712 — Offline EIP-712 typed data (chain-agnostic, no RPC): domain + types + primaryType + message JSON in, the normalized typed data plus domainSeparator, hashStruct and the final digest (the 32-byte value the wallet signs) out — with an optional signature (0x+65 bytes) it recovers the signer address (ecrecover), confirmed against an optional expectedAddress (recover.ok). Structs nest (arrays of structs, custom domain types like Permit2), uintN as decimal string or 0x hex, addresses 0x+40hex, bytes as 0x hex. Build/check the typed data your wallet signs (Permit/Permit2/relayer/off-chain votes) and verify who signed it, in one call. Pure cryptography: no RPC, no explorer, no API key, instant response, 100% margin (0.1 USDC on Base)
• GET /encode — Offline calldata encoder (mirror of /decode): given the FUNCTION NAME (transfer/approve/transferFrom/swapExact*Tokens*/deposit/withdraw/mint/burn/supply/borrow/repay/multicall/addLiquidity/removeLiquidity/safeTransferFrom/setApprovalForAll/execute/execTransaction — same ~40-function dictionary) or the 4-byte SELECTOR, plus the arguments as JSON (named object or positional array), returns the raw calldata hex ready to sign, with an embedded round-trip verification (verify.function shows the decoded call — what this calldata will execute). No RPC, no explorer, no API key: pure ABI encoding, instant response, 100% margin (0.1 USDC on Base)
• GET /decode — Offline calldata decoder: given raw transaction calldata (hex), returns the 4-byte selector, the known function (dictionary of ~40 functions: transfer/approve/swap/deposit/withdraw/mint/burn/supply/borrow/repay/multicall/addLiquidity/removeLiquidity/safeTransferFrom/setApprovalForAll/execute/execTransaction...) with TYPED, named arguments decoded, plus NESTED decoding of inner sub-calls (multicall bytes[], Gnosis Safe execute/execTransaction) — what this calldata will execute, before you sign or relay it. No RPC, no explorer, no API key: pure ABI decoding, instant response (0.1 USDC on Base)
• GET /wallet — One-call wallet snapshot on Base, Optimism or Ethereum Mainnet: native ETH balance plus curated tokens (WETH/USDC/USDT/DAI + chain majors) or your own token list, each with formatted balance, USD price and value, plus total wallet value (no explorer API, no signup) (0.1 USDC on Base)
• GET /pairs — DEX pair discovery: every Uniswap V2 + Uniswap V3 pool (fees 100/500/3000/10000) of any ERC-20 token on Base, Optimism or Ethereum Mainnet against curated base tokens (WETH/USDC/USDT/DAI + chain majors, or your own list via bases=) — per-pool venue, address, feeTier, feePct, token0/token1 (symbol + decimals), tokenIsToken0, quote, spot priceInQuote (token per quote), priceUsd, liquidityUsd (V2: 2 x quote reserve x price; V3: virtual TVL approximation 2 x L x sqrt(P)), reserves (V2) or sqrtPriceX96 + liquidity (V3), plus count/truncated. Pairs with zero reserves are filtered; sorted by liquidity desc. All computed on-chain from the DEX factories (no indexer, no market API) (0.1 USDC on Base)
• GET /history — Wallet activity: ERC-20 Transfer history of any address (incoming/outgoing, any token — no token address needed) on Base, Optimism or Ethereum Mainnet — per-transfer direction, blockNumber, timestamp (unix + ISO), txHash, logIndex, token address and decoded Transfer (from/to/value formatted with the token's own decimals), plus the native ETH balance delta over the window (before/after when the RPC supports historical balances). The did-my-payment-land check for payouts, bounties and airdrops. Busy wallets auto-shrink the window to what the RPC accepts (rangeHint) (0.1 USDC on Base)
• GET /events — On-chain events: raw event logs (eth_getLogs) of any contract or wallet on Base, Optimism or Ethereum Mainnet — block range filters, per-event timestamp, txHash and logIndex, with Transfer (from/to/value formatted with the contract decimals), Approval (owner/spender/value) and Uniswap V3 Swap (sender/recipient/amount0/amount1/sqrtPriceX96/liquidity/tick) decoded best-effort; other events returned raw for client-side decoding; busy contracts auto-shrink the range to what the RPC accepts (rangeHint) (0.1 USDC on Base)
• GET /multicall — On-chain MultiCall batch: up to 20 read-only eth_calls (balances, allowances, any call) in one request via the canonical Multicall3 contract on Base, Optimism or Ethereum Mainnet — per-call success flag + returnData, blockNumber and gas estimate; a reverting call returns success:false without failing the batch (0.1 USDC on Base)
• GET /swap — On-chain swap quote on Base: amountOut for an amountIn of any ERC-20 pair with DEX liquidity — direct pool (Uniswap V3 best liquidity / Aerodrome V2) or WETH route, with spot price, price impact and minOut slippage guards (0.5%/1%), all computed from pool reserves (no market API) (0.1 USDC on Base)
• GET /simulate — Transaction simulation on Base, Optimism or Ethereum Mainnet: eth_call pre-flight of from/to/data/value — success flag, return data, decoded revert reason (Error(string)) and gas estimate, on-chain (no explorer API) (0.1 USDC on Base)
• GET /allowance — ERC-20 allowance on Base, Optimism or Ethereum Mainnet: how much a spender contract/address can spend from an owner wallet — token, owner, spender, allowance (wei + formatted), decimals, symbol and block number, on-chain (no explorer API) (0.1 USDC on Base)
• GET /block — Block data on Base, Optimism or Ethereum Mainnet: number, hash, timestamp (unix + ISO), baseFee (wei + gwei), gasUsed/gasLimit, transactionCount, proposer and size for latest, earliest or any block number — the network snapshot call (proof of time, network cost and activity) before sending anything (0.1 USDC on Base)
• GET /tx-full — Full transaction intel on Base, Optimism or Ethereum Mainnet: raw tx (from/to/value, nonce, type, EIP-1559 fees, input calldata) + receipt (success/reverted, gas, logs) + block timestamp + confirmations + decoded function call (4-byte selector against a dictionary of ~40 known functions with typed args) + event summary (Transfer/Approval/Swap/Deposit...) — what did this tx do and what did it cost, in one call (0.1 USDC on Base)
• GET /price — Token prices on Base, Optimism or Ethereum Mainnet: spot USD price, supply and market cap for up to 30 tokens at once, computed on-chain from the most liquid DEX pool (Uniswap V3 + Uniswap V2) (0.1 USDC on Base)
• GET /ens — ENS name resolution on Ethereum Mainnet, Base or Optimism: forward (name to address) and reverse (address to ENS name) via the ENS registry on-chain — the identity check before paying a counterparty (0.1 USDC on Base)

+2 more endpoints.