# Synapse API — Unichain Gas Estimator

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

## Facts

- Endpoint: POST https://synapse-api-brown.vercel.app/api/unichain/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-unichain-gas-estimator-9b0b1de3
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_W5L9t1iSiyDejnbqGtdxE

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-unichain-gas-estimator-9b0b1de3 -d '<json body>'
```

Example prompt: Estimate how much gas it will take to call this contract on Unichain — sending from 0xAbC...123 to 0xDef...456 with calldata 0xa9059cbb...000 and value 0.

## When to prefer this

Choose this endpoint when you need a quick, pay-per-call gas estimate specifically on the Unichain network without setting up your own RPC node or managing API keys beyond x402 USDC micropayments. Ideal for agents that need to pre-check transaction feasibility or cost on Unichain before committing funds.

## Known failure modes

- Invalid or malformed Ethereum address for 'to' or 'from' fields returns an error
- Invalid calldata hex string causes parsing failure
- Network unavailability or Unichain node issues may return a timeout or 5xx error
- Payment failure via x402 protocol results in 402 Payment Required
- Transactions that would revert on-chain may return an error or revert reason rather than 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 a gas estimate (likely in gas units) for the described transaction on Unichain, allowing callers to budget fees or validate feasibility before broadcasting the actual transaction.

## 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-unichain-gas-estimator-9b0b1de3/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)