# Phantom API — Gas Estimation for On-Chain Transactions

> Phantom API — Gas Estimation for On-Chain Transactions is a paid API for AI agents from phantom-api-omega.vercel.app, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-20).

Estimates the gas cost for an Ethereum-compatible transaction given sender, recipient, calldata, and value fields across 57+ blockchain networks.

## Facts

- Endpoint: POST https://phantom-api-omega.vercel.app/api/plasma/gas/estimate?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-20
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/phantom-api-gas-estimation-for-on-chain-transactions-aa9661fd
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_qI4WO-lNSwMzNHHnWgmEx

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 phantom-api-gas-estimation-for-on-chain-transactions-aa9661fd -d '<json body>'
```

Example prompt: Estimate the gas needed to call this contract at 0xAbC123... with the calldata 0xa9059cbb... and a value of 0.1 ETH, sent from my wallet at 0xDef456...

## When to prefer this

Choose this endpoint when you need a fast, pay-per-call gas estimation across a wide range of EVM-compatible chains without managing your own node infrastructure. Ideal for agents that need to simulate transaction costs before execution, especially when multi-chain support (57+ networks) is needed without a long-term subscription.

## Known failure modes

- Invalid or malformed address in 'to' or 'from' fields returns an error
- Malformed calldata in 'data' field causes simulation failure
- Unsupported network or chain context results in an error response
- Payment not received or insufficient USDC results in 402 rejection
- Contract at target address reverts during simulation, causing estimation failure

## How this service works

Lightning-fast access to blockchain data, smart contract insights, and Web3 infrastructure across 57+ networks. Pay-per-call via x402.

## Output

Returns an estimated gas amount (in gas units) for the described transaction, allowing the caller to anticipate transaction costs and configure gas limits before submitting to a blockchain network.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "to": {
   "type": "string"
  },
  "data": {
   "type": "string"
  },
  "from": {
   "type": "string"
  },
  "value": {
   "type": "string"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/phantom-api-gas-estimation-for-on-chain-transactions-aa9661fd/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from phantom-api-omega.vercel.app](https://www.zero.xyz/host/phantom-api-omega.vercel.app/llms.txt)