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Api Endpoint

TxSim Decoder

Simulate an EVM transaction before signing. Decodes the calldata into a named function with arguments and security risk flags, AND runs a keyless static eth_call preview to tell you whether the transaction would succeed or revert (with the decoded revert reason). Use it to catch a failing or malicious transaction before you broadcast it. Read-only, no keys, no node infra. Asset-level change tracing is v2.

Open interactive test console

Offering

Provider
simulate.cyberwarex.com
Method
GET
Offering type
Api Endpoint
Transport type
http
Category
Other
Delivery
Not provided
Pricing model
Not provided
x402 version
2

Endpoint context

URL
https://simulate.cyberwarex.com/simulate
MIME type
application/json
First seen
2026-10-23T22:14:09.550Z
Last seen
Tags
tx-simulation, eth-call, calldata, Security, EVM

Website

Payment pricing

x402 payment terms are the authoritative price for calling this endpoint.

Payment option 1
0.005 USDC
Atomic price: 5000 · Network: eip155:8453 · Asset: USDC · Scheme: exact
Raw x402 terms
[
  {
    "scheme": "exact",
    "network": "eip155:8453",
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "amount": "5000",
    "payTo": "0x058D0Cc5CC97e61e8A9f38D6d6365bce525921B2"
  }
]

Observed health

Status
Healthy
Latest latency
375 ms
Average latency
829 ms
HTTP status
402
Last checked
Reachability
100% over 8 checks

Latency is measured to the first response headers. A reachable result does not verify response accuracy or merchant identity.

Input schema

{
  "type": "object",
  "properties": {
    "type": {
      "type": "string",
      "const": "http"
    },
    "method": {
      "type": "string",
      "enum": [
        "GET",
        "HEAD",
        "DELETE"
      ]
    },
    "queryParams": {
      "type": "object",
      "properties": {
        "chain": {
          "type": "string",
          "enum": [
            "base",
            "ethereum",
            "arbitrum",
            "optimism",
            "polygon",
            "bsc"
          ],
          "default": "base",
          "description": "EVM chain to simulate on."
        },
        "from": {
          "type": "string",
          "pattern": "^0x[a-fA-F0-9]{40}$",
          "description": "Sender address for the eth_call preview."
        },
        "to": {
          "type": "string",
          "pattern": "^0x[a-fA-F0-9]{40}$",
          "description": "Target contract or account address."
        },
        "value": {
          "type": "string",
          "description": "Native value in wei (optional, decimal or 0x hex)."
        },
        "data": {
          "type": "string",
          "pattern": "^0x[a-fA-F0-9]*$",
          "description": "Transaction calldata (hex)."
        }
      },
      "required": [
        "to"
      ],
      "additionalProperties": false
    }
  },
  "required": [
    "type",
    "method"
  ],
  "additionalProperties": false
}

Output schema

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "properties": {
    "input": {
      "additionalProperties": false,
      "properties": {
        "method": {
          "enum": [
            "GET",
            "HEAD",
            "DELETE"
          ],
          "type": "string"
        },
        "queryParams": {
          "additionalProperties": false,
          "properties": {
            "chain": {
              "default": "base",
              "description": "EVM chain to simulate on.",
              "enum": [
                "base",
                "ethereum",
                "arbitrum",
                "optimism",
                "polygon",
                "bsc"
              ],
              "type": "string"
            },
            "data": {
              "description": "Transaction calldata (hex).",
              "pattern": "^0x[a-fA-F0-9]*$",
              "type": "string"
            },
            "from": {
              "description": "Sender address for the eth_call preview.",
              "pattern": "^0x[a-fA-F0-9]{40}$",
              "type": "string"
            },
            "to": {
              "description": "Target contract or account address.",
              "pattern": "^0x[a-fA-F0-9]{40}$",
              "type": "string"
            },
            "value": {
              "description": "Native value in wei (optional, decimal or 0x hex).",
              "type": "string"
            }
          },
          "required": [
            "to"
          ],
          "type": "object"
        },
        "type": {
          "const": "http",
          "type": "string"
        }
      },
      "required": [
        "type",
        "method"
      ],
      "type": "object"
    },
    "output": {
      "properties": {
        "example": {
          "properties": {
            "asset_changes": {
              "description": "v2: needs a tracing RPC key.",
              "type": "null"
            },
            "chain": {
              "type": "string"
            },
            "decoded": {
              "description": "function, signature, args.",
              "type": "object"
            },
            "disclaimer": {
              "type": "string"
            },
            "note": {
              "type": "string"
            },
            "revert_reason": {
              "type": [
                "string",
                "null"
              ]
            },
            "risk": {
              "description": "level (none|caution|danger) + flags.",
              "type": "object"
            },
            "to": {
              "type": "string"
            },
            "would_succeed": {
              "type": [
                "boolean",
                "null"
              ]
            }
          },
          "type": "object"
        },
        "type": {
          "type": "string"
        }
      },
      "required": [
        "type"
      ],
      "type": "object"
    }
  },
  "required": [
    "input"
  ],
  "type": "object"
}