# Synapse API — Blockchain Gas Estimator

> Synapse API — Blockchain 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 a blockchain network given sender, recipient, calldata, and value

## Facts

- Endpoint: POST https://synapse-api-brown.vercel.app/api/stable/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-blockchain-gas-estimator-b09c356e
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_834LrXaEnC2XepxbFAX6E

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-blockchain-gas-estimator-b09c356e -d '<json body>'
```

Example prompt: Estimate the gas for a transaction from 0xAbc123... to 0xDef456... with calldata 0xa9059cbb... and a value of 0 ETH, so I know if it's safe to submit.

## When to prefer this

Use this endpoint when you need a quick, pay-per-call gas estimate for a blockchain transaction without maintaining your own RPC node. Prefer it over direct RPC calls when operating in a serverless or agent context where infrastructure management is undesirable. It supports 57+ blockchain networks, making it suitable for multi-chain use cases without configuring separate providers.

## Known failure modes

- Invalid or malformed address in 'to' or 'from' fields returns an error
- Malformed calldata hex string causes a parsing error
- Unavailable or unsupported chain context may return an error or null estimate
- Network timeout or RPC failure on the backend returns a 5xx error
- Missing required fields results in a 400 validation error

## 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, allowing agents to assess transaction feasibility and fee costs before submission.

## 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-blockchain-gas-estimator-b09c356e/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)