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

# Horizontal Concurrency

> Scale browser sessions across the infrastructure you provide

## Overview

Rusty Browser can run many browser sessions in parallel. In open-source deployments, practical concurrency is determined by your server, Redis, Flux configuration, and the compute capacity available to browser agents.

The open-source stack scales according to the infrastructure you provide.

## Architecture

Each browser instance is isolated:

* No shared browser state between sessions
* Independent browser agent processes
* Failures are contained to the affected browser
* Resources are released when sessions are closed

## Scaling Model

For local development, Flux can run browser agents as subprocesses on the same machine. For larger deployments, Flux can provision and coordinate agents across the infrastructure providers you configure.

```text theme={null}
1 browser      -> 1 browser agent
100 browsers   -> 100 browser agents
N browsers     -> N browser agents, limited by available capacity
```

## Capacity Planning

Plan capacity around the sites and workflows you automate:

* CPU and memory per browser
* Expected browser lifetime
* Number of concurrent instructions
* Redis and network throughput
* Any AI, proxy, or captcha providers you configure yourself

## Cleanup at Scale

Concurrency depends on releasing resources promptly. Close individual browsers when a workflow finishes, or use `DELETE /browsers/` to close all active sessions during test teardown or recovery.