<!-- source: https://secondlayer.tools/docs/api-reference#get-mempool-transaction -->

## Pending transaction by tx_id

`GET /v1/index/mempool/{tx_id}`

One pending transaction. It 404s once the transaction confirms (read it from `/v1/index/transactions/{tx_id}`) or drops. Never cached.

### Path parameters

| Name | Type | Description |
| --- | --- | --- |
| `tx_id` | string, required | Transaction id, `0x`-prefixed hex. |

### Responses

- `200` The pending transaction and the current tip
- `401` This bind requires the instance token, and it was missing or wrong
- `404` Not pending on this instance: confirmed, dropped, or never seen (`Pending transaction not found`)
- `429` Rate limited; retry after `Retry-After` seconds

### Example

```bash
curl https://api.secondlayer.tools/v1/index/mempool/{tx_id} \
  -H "Authorization: Bearer $SECONDLAYER_API_KEY"
```

```json
{
  "transaction": {
    "cursor": "bToyNjg4Mjc0",
    "tx_id": "0x00a5cd852c25c5bb5cc7f97c60b88a6a635c001ad431e2133f366be85d5ce0f0",
    "tx_type": "token_transfer",
    "sender": "SM1Z09F6431EQT8GCTEF496TCT5JDTPJ3VFF9Q766",
    "received_at": "2026-09-23T15:11:05.629Z",
    "fee": "1732",
    "nonce": "37",
    "sponsored": false,
    "anchor_mode": "any",
    "post_condition_mode": "deny",
    "post_conditions": [],
    "token_transfer": {
      "recipient": "SMJWA5YRH2DRANX3V96Z6JJSFBE03Z9Y0WHN3XSQ",
      "amount": "79559850769",
      "memo": "572826509"
    }
  },
  "tip": {
    "block_height": 9048938,
    "finalized_height": 9048671,
    "lag_seconds": 23,
    "source_block_height": 9048938
  }
}
```