# Synapse API — Gas Estimation for EVM Transactions

> Synapse API — Gas Estimation for EVM Transactions 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 required for a transaction on a blockchain network by simulating execution with the provided transaction parameters.

## Facts

- Endpoint: POST https://synapse-api-brown.vercel.app/api/humanity/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-gas-estimation-for-evm-transactions-b3b0f607
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_49zla35ek4ZP2nC6psmw3

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-gas-estimation-for-evm-transactions-b3b0f607 -d '<json body>'
```

Example prompt: Estimate the gas needed for a transaction from 0xAbC...123 to contract 0xDef...456 with calldata 0xa9059cbb...0001 and a value of 0 ETH.

## When to prefer this

Use this endpoint when you need a quick, pay-per-call gas estimate for an EVM-compatible transaction without running your own node or maintaining an RPC connection. Ideal for AI agents that need to validate transaction feasibility or budget gas costs before executing on-chain operations across any of the 57+ supported blockchain networks.

## Known failure modes

- Invalid or malformed address in 'to' or 'from' fields returns an error
- Malformed calldata in 'data' field causes simulation failure
- Transaction would revert on-chain, causing the estimate call to fail or return an error
- Missing required fields may result in a 400 bad request
- Network congestion or node unavailability may cause timeouts

## 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 unit amount representing the computational cost of executing the described transaction on the target blockchain network. This helps callers budget gas fees before submitting 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-gas-estimation-for-evm-transactions-b3b0f607/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)