> ## Documentation Index
> Fetch the complete documentation index at: https://docs.nexroute.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Async mode

> Optimistic backruns behind partner-dispatched transactions

In Async mode, you send a copy of the fully user-signed transaction to a dedicated nexroute endpoint and dispatch it yourself, without waiting for a response. nexroute evaluates the transaction for backrun opportunity and optimistically races a backrun in behind it through private partnerships. Your dispatch path is untouched: no added hop, no added latency.

This is one of three integration modes for [Cashback](/cashback). Pick Async mode when you control transaction dispatch but can't afford a synchronous round trip before it: typically chains with very low block intervals, where any delay costs inclusion position. If you can hand dispatch to nexroute, [Dispatch mode](/cashback/dispatch) offers stronger guarantees; if the user's wallet dispatches, see [Embedded mode](/cashback/embedded).

## What you get

* **Zero added latency**: notification is fire-and-forget, sent in parallel with your own dispatch
* **Backrun monetization, best-effort**: where on-chain opportunities exist, nexroute races a backrun behind your transaction; when the backrun misses, your transaction is unaffected
* **Unchanged dispatch path**: you keep full control of how and where the transaction is broadcast
* **Non-interference**: notified transactions are never broadcast, front-run, or leaked; they are used solely for backrun construction

## How it works

1. You sign a user transaction in your normal flow
2. You POST it to your dedicated Cashback endpoint as a JSON-RPC `eth_notifyRawTransaction` request, without blocking your dispatch on the response
3. You dispatch the transaction yourself, exactly as you do today
4. nexroute evaluates the transaction for backrun opportunity, constructs the backrun, and submits it through private partnerships targeting inclusion directly behind your transaction
5. If the backrun lands, it executes as a separate transaction behind yours; if it doesn't, nothing changes for your transaction

Because nexroute never holds or bundles your transaction, the backrun is optimistic: it competes for the block position directly behind your transaction rather than being packed atomically with it. This is the trade that keeps your dispatch latency at zero.

## Reporting

A per-transaction explorer and aggregated reporting dashboard for inclusion status and partner activity is in active development. Contact nexroute for the current status.

## Get started

<CardGroup cols={2}>
  <Card title="Quickstart" icon="bolt" href="/cashback/async/quickstart">
    Send your first notification to your Cashback endpoint.
  </Card>

  <Card title="Authentication" icon="key" href="/cashback/async/authentication">
    How endpoints are secured per partner.
  </Card>

  <Card title="Security" icon="shield-check" href="/cashback/async/security">
    Privacy and non-interference guarantees.
  </Card>

  <Card title="Rate Limiting" icon="gauge" href="/cashback/async/rate-limiting">
    Burst handling and capacity behavior.
  </Card>
</CardGroup>