# Synapse API — Soneium Gas Estimator

> Synapse API — Soneium 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 the gas cost for a transaction on the Soneium blockchain network before submission

## Facts

- Endpoint: POST https://synapse-api-brown.vercel.app/api/soneium/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-soneium-gas-estimator-e808342c
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_WBr9qR6oj_PDa5a2cfpzK

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-soneium-gas-estimator-e808342c -d '<json body>'
```

Example prompt: Before I send this transaction on Soneium — from 0xAbCd...1234 to 0x5678...EfGh with a value of 0.1 ETH and calldata 0xabcdef — can you estimate how much gas it'll cost?

## When to prefer this

Use this endpoint when you need a gas estimate specifically for the Soneium blockchain network before committing to a transaction. Prefer this over generic gas estimation tools when your transaction targets a Soneium contract or address, and you want a pay-per-call approach without managing RPC infrastructure yourself.

## Known failure modes

- Invalid or malformed address fields (to/from) may return a validation error
- Malformed or non-hex data field may cause estimation failure
- Insufficient or missing required fields may return a 400 Bad Request
- Soneium RPC node unavailability may cause timeouts or 503 errors
- Transactions that would revert on-chain may return an execution error instead of a gas estimate

## 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) required to execute the described transaction on the Soneium network, allowing callers to forecast fees before broadcasting 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-soneium-gas-estimator-e808342c/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)