# Base Transaction Lookup API

> Base Transaction Lookup API is a paid API for AI agents from base-facts.yankii.fr, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-11).

Fetches on-chain details for a specific Base mainnet transaction by its hash, including gas, status, transfers, and block info

## Facts

- Endpoint: POST https://base-facts.yankii.fr/v1/tx?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-11
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/base-transaction-lookup-api-b497f969
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_l9SQD0hPBK8Qj4E0BNSWe

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 base-transaction-lookup-api-b497f969 -d '<json body>'
```

Example prompt: Can you look up the details for this Base transaction — 0x4a3b...f9c2 — I need to know if it succeeded, how much gas was used, and whether there were any ERC-20 transfers?

## When to prefer this

Use this endpoint when you need detailed on-chain facts about a specific Base mainnet transaction — particularly when you need gas metrics, ERC-20 transfer data, status confirmation, or timestamp/block info — and you are operating in a context where x402 micropayments are supported.

## Known failure modes

- Invalid or malformed transaction hash returns an error
- Transaction hash not found on Base mainnet (e.g. wrong network)
- RPC node timeout or connectivity issues
- Hash exists but transaction is still pending
- Payment of 0.003 USDC not fulfilled, returns 402 Payment Required

## How this service works

Get transaction status, fee, and decoded ERC20 Transfer events

## Output

Returns a JSON object with the transaction's to/from addresses, hash, status (success/failure), gas used, effective gas price, fee in ETH, block number, Unix timestamp, ERC-20 transfers array, and contract address if applicable — all sourced from Base mainnet RPC.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "hash": {
   "type": "string",
   "description": "0x-prefixed 32-byte transaction hash"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "to": "0x...",
  "from": "0x...",
  "hash": "0x...",
  "feeEth": "0.000000021",
  "source": "base-mainnet-rpc",
  "status": "success",
  "gasUsed": "21000",
  "timestamp": "1700000000",
  "blockNumber": "52130000",
  "erc20Transfers": [],
  "contractAddress": null,
  "effectiveGasPrice": "100000000"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/base-transaction-lookup-api-b497f969/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from base-facts.yankii.fr](https://www.zero.xyz/host/base-facts.yankii.fr/llms.txt)