> For the complete documentation index, see [llms.txt](https://docs.ethgas.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.ethgas.com/orderflow/searchers.md).

# Searchers

Searchers receive live orderflow over WebSocket and submit bundles over the same connection or HTTP.

To request a searcher account, contact us at <info@ethgas.com>.

| Transport | Endpoint                                             |
| --------- | ---------------------------------------------------- |
| WebSocket | `wss://searcher.orderflow.ethgas.com/v1/{API_KEY}`   |
| HTTP      | `https://searcher.orderflow.ethgas.com/v1/{API_KEY}` |

## Receive orderflow

Opening the WebSocket subscribes the session automatically. A client may also send the idempotent subscription request:

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "eth_subscribe",
  "params": ["ethgas_partialPendingBundles"]
}
```

The params can also be `mevblocker_partialPendingBundles` or `blink_partialPendingBundles` for compatibility to other protocols.

Notifications contain an ordered array of decoded unsigned transactions. This abridged example omits some type-specific fee fields:

```json
{
  "jsonrpc": "2.0",
  "method": "eth_subscription",
  "params": {
    "subscription": "0x...",
    "result": [{
      "chainId": "0x1",
      "to": "0x...",
      "value": "0x0",
      "data": "0x...",
      "nonce": "0x1",
      "gas": "0x5208",
      "type": "0x2",
      "hash": "0x...",
      "from": "0x..."
    }]
  }
}
```

Fanout is live-only: open the WebSocket before the originator submits. Missed notifications are not replayed.

If the `result` array contains only 1 object, it is a transaction only. If it contains more than 1 object, that is a bundle. You only need to reference the hash of the last transaction in your backrun bundle.

`eth_unsubscribe` is not supported. To stop receiving orderflow, close the WebSocket connection.

## Submit a backrun

Use the last transaction hash from the notification as the first `txs` entry, followed by your signed transaction(s):

```json
{
  "jsonrpc": "2.0",
  "id": 2,
  "method": "eth_sendBundle",
  "params": [{
    "txs": ["0x<ORIGINATOR_REFERENCE_HASH>", "0x<SIGNED_BACKRUN>"],
    "blockNumber": "0x12abcde",
    "replacementUuid": "aaaaaaaa-bbbb-4ccc-8ddd-eeeeeeeeeeee",
    "revertingTxHashes": [],
    "droppingTxHashes": []
  }]
}
```

The response returns a local `bundleHash`. The engine expands a valid originator reference server-side and adds the applicable refund fields before builder submission.

`txs` accepts 0–100 entries. An empty `txs` array is a cancellation by `replacementUuid` and behaves identically to `eth_cancelBundle`; in this case `replacementUuid` is required and no other field is permitted.

`replacementUuid` is optional for submission. When used, increase either `replacementSeqNumber` or its alias `replacementNonce`; do not send both.

`minTimestamp` is an optional unsigned Unix timestamp in seconds. It must not be later than the bundle's intake time; future values are rejected rather than queued.

## Cancel replacements

```json
{
  "jsonrpc": "2.0",
  "id": 3,
  "method": "eth_cancelBundle",
  "params": [{
    "replacementUuid": "aaaaaaaa-bbbb-4ccc-8ddd-eeeeeeeeeeee"
  }]
}
```

A successful `eth_cancelBundle` response contains the integer `200` in the JSON-RPC `result` field, over either HTTP or WebSocket:

```json
{"jsonrpc":"2.0","id":3,"result":200}
```

An empty `txs` bundle with only `replacementUuid` is also a cancellation, but its JSON-RPC result is `{"bundleHash":""}`. Both responses confirm durable cancellation admission; builder completion is asynchronous.

## Connection behavior

Respond to pings promptly. Sessions close after 24 hours and should reconnect. Authorization changes close the connection, and slow readers may be disconnected when their outbound queue fills.


---

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