# Synapse API — Optimism Gas Estimator

> Synapse API — Optimism Gas Estimator is a paid API for AI agents from synapse-api-brown.vercel.app, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-15).

Estimates gas costs for a transaction on the Optimism (OP Mainnet) blockchain given sender, recipient, calldata, and value.

## Facts

- Endpoint: POST https://synapse-api-brown.vercel.app/api/optimism/gas/estimate
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/synapse-api-optimism-gas-estimator-3c258b59
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_GqLr4QiRjndVFPvdQ_KXo

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 synapse-api-optimism-gas-estimator-3c258b59 -d '<json body>'
```

Example prompt: Estimate the gas cost for sending 0.5 ETH on Optimism from 0xAbCd...1234 to 0xDeFg...5678 with no calldata.

## When to prefer this

Use this endpoint when you need a quick, pay-per-call gas estimate specifically for the Optimism (OP Mainnet) L2 network without running your own node. It is preferable when you want a lightweight, pre-submission cost check for ETH transfers or contract calls on Optimism and don't need a full node setup or SDK integration.

## Known failure modes

- Invalid or malformed address in 'to' or 'from' fields returns a 4xx error
- Invalid hex calldata in 'data' field causes a parsing error
- Optimism node unavailability results in a 5xx or timeout
- Insufficient or missing required fields may return a validation error
- Transaction simulation reverts (e.g. contract call would fail) may return an error or revert reason

## How this service works

High-speed API suite for AI processing, web scraping, and smart data utilities across 57+ blockchain networks. Pay-per-call via x402.

## Output

Returns an estimated gas amount (in gas units) needed to execute the specified transaction on Optimism, helping callers budget fees before submitting the transaction on-chain.

## 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/synapse-api-optimism-gas-estimator-3c258b59/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from synapse-api-brown.vercel.app](https://www.zero.xyz/host/synapse-api-brown.vercel.app/llms.txt)