# Web3 Smart Contract Audit API

> Web3 Smart Contract Audit API is a paid API for AI agents from upturned-penniless-obedient.ngrok-free.dev, paid per call via x402, $0.000001/call, status unknown (last checked 2026-10-10).

Analyzes smart contract code for security vulnerabilities, bugs, and audit findings on a specified blockchain

## Facts

- Endpoint: POST https://upturned-penniless-obedient.ngrok-free.dev/v1/web3-audit?utm_source=zero.xyz
- Price: $0.000001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-10
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/web3-smart-contract-audit-api-969ff6c8
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Z4M9iJ69kig7zWMvUie8t

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 web3-smart-contract-audit-api-969ff6c8 -d '<json body>'
```

Example prompt: Can you audit this Solidity smart contract code for security vulnerabilities on the Ethereum mainnet? Here's the code: `pragma solidity ^0.8.0; contract Token { mapping(address => uint256) balances; function withdraw(uint256 amount) public { require(balances[msg.sender] >= amount); (bool success,) = msg.sender.call{value: amount}(""); balances[msg.sender] -= amount; } }`

## When to prefer this

Use this endpoint when you need a quick, low-cost automated security audit of smart contract source code before deployment. It is ideal for individual developers or agents running pre-deployment checks on Ethereum, BSC, Polygon, or other EVM-compatible chains. Prefer this over manual review for rapid iteration cycles or when budget is a constraint at $0.000001 USDC per call.

## Known failure modes

- Missing 'code' field returns validation error
- Invalid or empty code string may produce no findings or an error
- Unsupported chain identifier may default to generic analysis or return an error
- ngrok free-tier tunnel may be offline or rate-limited, returning 502 or connection errors
- Malformed Solidity/contract code may cause parsing failures
- Very large contracts may timeout

## How this service works

ngrok is the fastest way to put anything on the internet with a single command.

## Output

Returns a security audit report for the submitted smart contract code, including identified vulnerabilities, severity ratings, descriptions of potential exploits, and recommendations for remediation. Output is specific to the provided blockchain chain context.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "code"
 ],
 "properties": {
  "code": {
   "type": "string"
  },
  "chain": {
   "type": "string"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/web3-smart-contract-audit-api-969ff6c8/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from upturned-penniless-obedient.ngrok-free.dev](https://www.zero.xyz/host/upturned-penniless-obedient.ngrok-free.dev/llms.txt)