# OBOL EVM Transaction Preflight Simulator

> OBOL EVM Transaction Preflight Simulator is a paid API for AI agents from obol-x402.fly.dev, paid per call via x402, $0.1/call, status down (last checked 2026-09-15).

Simulates an EVM transaction before execution to predict success, revert reason, and gas estimate as a pre-trade safety verdict

## Facts

- Endpoint: GET https://obol-x402.fly.dev/v1/evm/simulate
- Price: $0.1/call
- Payment: x402
- Status: down
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/obol-evm-transaction-preflight-simulator-26df1d4e
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_vgA8Bz_8NO6hJRPQQAHMJ

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability obol-evm-transaction-preflight-simulator-26df1d4e
```

Example prompt: Before I broadcast this swap transaction on Base, simulate it to check whether it will revert and give me the gas estimate — the calldata is 0x38ed1739...deadbeef, sender is 0xAbC...123, on chain ID 8453.

## When to prefer this

Use OBOL's EVM simulate endpoint when you need a fast, pay-per-call preflight check on a specific transaction before broadcasting — especially in agentic DeFi workflows on Base, Ethereum, Arbitrum, Optimism, Polygon, or BNB Chain where reverting wastes gas or triggers undesirable state. Prefer this over generic RPC eth_call when you want a structured, signed verdict with gas estimate in one call, no API key setup, and USDC micropayment billing.

## Known failure modes

- Unsupported chain ID — endpoint may not support all EVM networks
- Invalid or malformed calldata returns an error or unexpected revert
- RPC node unavailability on the target chain causing simulation failure
- Paid endpoint — missing or insufficient USDC payment on Base results in 402 response
- Simulation reflects current chain state; state changes between simulation and broadcast can alter outcome
- Contract not yet deployed or self-destructed returns a revert

## How this service works

Pre-trade safety for AI agents on Base, Ethereum, Arbitrum, Optimism, Polygon, BNB and Robinhood Chain. Is this token a rug — and can I sell it again? Signed verdicts before you buy, approve, send or sign: token rug/honeypot check with buy-sell tax, honeypot sell-simulation, pre-sign calldata guard (unlimited-approve / setApprovalForAll / drain-in-multicall), wallet risk with sanctions screening, tx preflight, and a launch feed with safety overlays. Plus unique Bitcoin forensics no RPC gives you: money-graph role, whale and exchange fingerprinting, Satoshi-era provenance, validation-gated block anomalies, and broadcast-fee timing. Every response Ed25519-signed and independently verifiable. Pay-per-call USDC on Base — no keys, no accounts, no signup. Free: /catalog, /llms.txt, and a preview for every paid SKU.

## Output

Returns a JSON object with a 'verdict' field ('will_succeed' or similar), a 'revert' field (null if transaction will succeed, or a revert reason string), and a 'gas_estimate' integer representing predicted gas units. All responses are Ed25519-signed for independent verifiability.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "to"
     ],
     "properties": {
      "to": {
       "type": "string"
      },
      "data": {
       "type": "string"
      },
      "from": {
       "type": "string"
      },
      "chain": {
       "enum": [
        "base",
        "ethereum",
        "arbitrum",
        "optimism",
        "polygon",
        "bnb",
        "robinhood"
       ],
       "type": "string",
       "default": "base"
      },
      "value": {
       "type": "string"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "revert": null,
  "verdict": "will_succeed",
  "gas_estimate": 52000
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/obol-evm-transaction-preflight-simulator-26df1d4e/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from obol-x402.fly.dev](https://www.zero.xyz/host/obol-x402.fly.dev/llms.txt)