# BaseBrief x402 – Base Chain Gas Oracle

> BaseBrief x402 – Base Chain Gas Oracle is a paid API for AI agents from basebrief-x402.savannah-5966.chatgpt.site, paid per call via x402, $0.004/call, status unknown (last checked 2026-09-15).

Returns real-time gas prices, wallet balances, token metadata, and ERC-20 allowances from the Base mainnet blockchain for $0.004 per call.

## Facts

- Endpoint: GET https://basebrief-x402.savannah-5966.chatgpt.site/api/v1/base/gas
- Price: $0.004/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/basebrief-x402-base-chain-gas-oracle-beca6f99
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_dqs7jN9AEHpUSJgnS-Kow

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 basebrief-x402-base-chain-gas-oracle-beca6f99
```

Example prompt: What's the current gas price on Base mainnet, and what's the ETH balance and USDC allowance for wallet 0xAbC...123 approved to the Uniswap router?

## When to prefer this

Choose this endpoint when an AI agent needs live, point-in-time Base mainnet state — gas prices, balances, or ERC-20 allowances — without setting up a full RPC node or Alchemy/Infura account. At $0.004/call it is cost-effective for sporadic lookups. Prefer it over generic Ethereum RPC providers when you specifically need Base L2 data with a pay-per-use x402 micropayment model and no API key management.

## Known failure modes

- Invalid or malformed wallet/contract address returns an error or empty result
- Payment not received (x402 flow incomplete) results in 402 Payment Required response
- Base RPC node temporarily unavailable returns a 503 or timeout
- Querying a non-existent token contract returns null metadata
- Rate limiting if too many concurrent calls without payment
- Block reorganization edge cases may cause transient inconsistencies in pointInTime data

## How this service works

Gas, balances, token metadata and allowances for $0.004 per result.

## Output

A JSON object anchored to a specific Base mainnet block containing: current gas price/base fee, wallet ETH and token balances, ERC-20 token metadata (name, symbol, decimals), approved allowances for specified spender contracts, and evidence fields (chainId 8453, blockNumber, pointInTime flag) confirming the data is a snapshot from a live Base JSON-RPC node.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "required": {
   "type": "string"
  },
  "properties": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "evidence": {
   "chain": "Base mainnet",
   "chainId": 8453,
   "blockNumber": "35123456",
   "pointInTime": true
  },
  "limitations": [
   "Point-in-time direct Base JSON-RPC evidence."
  ]
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/basebrief-x402-base-chain-gas-oracle-beca6f99/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from basebrief-x402.savannah-5966.chatgpt.site](https://www.zero.xyz/host/basebrief-x402.savannah-5966.chatgpt.site/llms.txt)