AMNT Transaction Preflight

x402

AMNT Transaction Preflight is a paid API for AI agents from www.amnt.io, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-15).

Simulates an EVM transaction before signing and returns a safety verdict (safe/warn/danger) to help users avoid risky or malicious transactions.

Price / call$0.005

Seller volume →—

Success—

StatusUnknown

How this service works

Tx Preflight - Simulate a transaction before you sign it and get a safe / warn / danger verdict.

Output

Returns a safety verdict of safe, warn, or danger for the simulated transaction, along with contextual details about what the transaction would do — such as allowance changes, token transfers, or suspicious patterns detected during simulation.

Example use cases

Verify token approval before signing

“I'm about to approve a token spend on Base — can you preflight this transaction for me before I sign? The 'to' is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913, my wallet is 0xAbC123..., calldata is 0x095ea7b3000000000000000000000000someSpender, 0 wei, chain 8453.”

Check suspicious DeFi interaction

“I got a weird transaction request from a DeFi site — can you simulate it and tell me if it's safe or dangerous? It's on Ethereum mainnet (chain 1), to 0xDeadBeef..., from 0xMyWallet..., with this calldata: 0xdeadbeef1234..., no ETH value.”

Pre-approve airdrop claim safety check

“Before I claim this airdrop, run a preflight simulation on the transaction to make sure it won't drain my wallet — it's on Arbitrum (chain 42161), targeting 0xAirdropContract..., from 0xMyAddress..., calldata 0x4e71d92d, value 0.”

Technical details

Endpoint

POSThttps://www.amnt.io/api/os-tools/tx-preflight

When to prefer

Use this endpoint when an AI agent or user needs to assess the risk of an EVM transaction before signing — especially for approvals, DeFi interactions, or any calldata received from an untrusted source. Ideal for wallet UX flows, agent-driven DeFi automation, or phishing protection pipelines. Prefer this over static calldata decoders when you need a simulation-backed verdict rather than just ABI decoding.

Side effects

Invalid or malformed hex calldata returns an error
Unsupported chain ID (only 1, 10, 137, 8453, 42161 are supported)
Simulation may fail if the 'from' address has insufficient balance for the simulation
Contract not deployed at 'to' address causes simulation failure
Malformed Ethereum address format returns validation error

Input

Schema · Request body

Field	Type	Description
to	string	The contract or wallet this transaction is aimed at.
data	string	The transaction's data field, hex. Omit for a plain native-token send.
from	string	The wallet that would sign. Used for the simulation and the allowance read.
value	string	Native token sent with the call, in wei. Decimal string.
chainId	string	Which chain to simulate against.

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