{"slug":"402-com-tr-api-x402-simulate-tx-562b57","title":"Simulate an UNSIGNED transaction against live Base state before an agent signs","host":"402.com.tr","method":"GET","resource":"https://402.com.tr/api/x402/simulate-tx","category":"code","description":"Simulate an UNSIGNED transaction against live Base state before an agent signs: will it SUCCEED or revert (with the contract's own reason), the gas estimate and ETH cost, and — decoded from the calldata — whether it grants an approval, and whether that approval is UNLIMITED (approve/permit) or a set","price_listed":0.03,"price_asked":null,"state":"no_terms","state_label":"Answers HTTP 429 without x402 payment terms","checks_7d":1,"answered_7d":0,"latency_ms_median":null,"reported_calls_30d":2,"reported_payers_30d":1,"networks":["eip155:8453"],"badge":"unverified","paid_checks_7d":0,"paid_ok_7d":0,"example_input":{"method":"GET","pathParams":{},"queryParams":{"data":"0x095ea7b3000000000000000000000000cf77a3ba9a5ca399b7c97c74d54e5b1beb874e430000000000000000000000000000000000000000000000000000000000000000","from":"0x973a31858f4d2125f48c880542da11a2796f12d6","to":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","value":"0.1"},"type":"http"},"output_schema":{"$schema":"https://json-schema.org/draft/2020-12/schema","properties":{"input":{"additionalProperties":false,"properties":{"method":{"enum":["GET"],"type":"string"},"pathParams":{"type":"object"},"queryParams":{"properties":{"data":{"description":"Calldata (hex, optional)","type":"string"},"from":{"description":"Sender address","type":"string"},"to":{"description":"To (recipient/contract)","type":"string"},"value":{"description":"ETH value (optional)","type":"string"}},"required":["from","to"],"type":"object"},"type":{"const":"http","type":"string"}},"required":["type","method"],"type":"object"},"output":{"properties":{"example":{"type":"object"},"type":{"type":"string"}},"required":["type"],"type":"object"}},"required":["input"],"type":"object"},"history":[{"day":"2026-10-10","reachable":true,"status":429,"valid_402":false,"asked_usdc":null,"price_match":null,"latency_ms":339,"error":null}],"description_full":"Simulate an UNSIGNED transaction against live Base state before an agent signs: will it SUCCEED or revert (with the contract's own reason), the gas estimate and ETH cost, and — decoded from the calldata — whether it grants an approval, and whether that approval is UNLIMITED (approve/permit) or a setApprovalForAll, the classic drain vectors. Pass from, to, and optionally data (calldata) + value. The pre-execution check the agent-safety playbook says to run and block on. Not financial advice.","last_updated":"2026-10-09T11:05:56.436Z","schemes":["exact"]}