# Synapse API — Citrea Gas Estimator

> Synapse API — Citrea 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 2026-10-12).

Estimates the gas cost for a transaction on the Citrea blockchain network before submission

## Facts

- Endpoint: POST https://synapse-api-brown.vercel.app/api/citrea/gas/estimate?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/synapse-api-citrea-gas-estimator-9f40666f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_pY4Rhl3ZW4021AYr0QWL9

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-citrea-gas-estimator-9f40666f -d '<json body>'
```

Example prompt: Before I send this Citrea transaction from 0xAbc...123 to 0xDef...456 with calldata 0x1234abcd and 0 value, can you estimate how much gas it will use?

## When to prefer this

Use this endpoint when you need a gas estimate specifically on the Citrea network (a Bitcoin-rollup EVM chain) before submitting a transaction. Prefer this over generic Ethereum gas estimators when your transaction targets Citrea's specific chain environment. Ideal for pre-flight cost checks in dApps, wallets, or automated agents managing Citrea transactions.

## Known failure modes

- Invalid or malformed address in 'to' or 'from' fields returns a 400 error
- Malformed hex data in the 'data' field causes parsing failure
- Network unavailability of Citrea RPC node results in a 503 or timeout
- Invalid value format (non-hex or non-numeric string) causes validation error
- 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 an estimated gas units figure for the described Citrea transaction, allowing callers to predict fees before broadcasting to the network. Typically includes a numeric gas estimate (e.g. in units of gas) that can be combined with current gas price to derive total cost.

## 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-citrea-gas-estimator-9f40666f/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)