Simulate an UNSIGNED transaction against live Base state before an agent signs
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.
Paid test badge: not yet. The checks above are free: we call the tool without paying and read the payment request it sends back. The Verified badge needs paid calls whose answers match the promised output, and nobody can buy a badge.
Endpoint
GET https://402.com.tr/api/x402/simulate-tx
| Category | Code and developer |
|---|---|
| Provider host | 402.com.tr |
| Networks | eip155:8453 |
| Payment schemes | exact |
| Self-reported calls, 30 days | 2 from 1 payers (the provider's figure, not ours) |
Our checks, last 30 days
| Day | Result | HTTP | Asked | Time |
|---|---|---|---|---|
| 2026-10-10 | no x402 terms | 429 | 339 ms |
Example input (from the provider)
{
"method": "GET",
"pathParams": {},
"queryParams": {
"data": "0x095ea7b3000000000000000000000000cf77a3ba9a5ca399b7c97c74d54e5b1beb874e430000000000000000000000000000000000000000000000000000000000000000",
"from": "0x973a31858f4d2125f48c880542da11a2796f12d6",
"to": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"value": "0.1"
},
"type": "http"
}
Promised output schema (from the provider)
{
"$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"
}