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

# Browser fingerprinting

> Understand browser fingerprinting and how browser signals can affect Octoparse task reliability.

Browser fingerprinting is a method websites use to identify browser sessions based on signals such as device, browser, screen size, language, timezone, cookies, and behavior. These signals can affect whether a task loads normally, triggers a challenge, or gets blocked.

Octoparse uses browser-based extraction, so browser behavior and environment settings can influence task stability.

## What websites may check

Websites may evaluate:

* Browser type and version
* User agent
* Cookies and session state
* Language and timezone
* Screen size or viewport
* IP address and location
* Loading behavior
* Interaction timing
* Repeated request patterns

## Why it matters

Fingerprinting can cause tasks to behave differently across environments.

| Situation                        | Possible explanation                                 |
| -------------------------------- | ---------------------------------------------------- |
| Works locally but fails in cloud | Website treats the cloud environment differently     |
| Login expires unexpectedly       | Session or cookie signals changed                    |
| CAPTCHA appears during runs      | Website detected unusual browser or traffic behavior |
| Content differs by run           | Location, language, or session state changed         |
| Page loads incomplete content    | Browser or environment signals affect page behavior  |

## How to reduce fingerprint-related issues

<Steps>
  <Step title="Test locally first">
    Observe how the website behaves in the built-in browser.
  </Step>

  <Step title="Stabilize login and cookies">
    Use consistent login and cookie settings for session-dependent pages.
  </Step>

  <Step title="Control location when needed">
    Use [proxies](/docs/platform/proxy) if the website serves different content by region or IP.
  </Step>

  <Step title="Avoid aggressive runs">
    Add waits and avoid excessive frequency that looks unnatural.
  </Step>

  <Step title="Compare logs">
    Compare local and cloud run behavior using [logs](/docs/platform/logs-and-events) when failures appear only in one environment.
  </Step>
</Steps>

## Best practices

* Keep task behavior close to normal browsing patterns.
* Add waits for dynamic content.
* Avoid unnecessary repeated page reloads.
* Use stable sessions for login-required sites.
* Use proxies only when they solve a clear access or location issue.
* Re-test tasks after major website changes.

<Warning>
  Browser fingerprinting is controlled by the target website. Octoparse can help you configure more stable workflows, but it cannot guarantee that every website will allow automated extraction.
</Warning>