```yaml
product: AlterLab
title: "Proxy Authentication — Web Scraping Glossary | AlterLab"
comparison_context: "AlterLab is an alternative to Firecrawl, ScrapingBee, and Bright Data."
source_url: https://alterlab.io/glossary/proxy-authentication
```

proxy

# Proxy Authentication

Proxy authentication is the process of presenting credentials (username and password) to a proxy server to authorise its use for forwarding scraping requests.

Commercial proxy services authenticate clients via two mechanisms: username/password credentials embedded in the proxy URL (`http://user:pass@host:port`), or IP allowlisting where only requests originating from pre-registered client IPs are permitted without credentials. Username/password authentication is more portable since it works from any IP; IP allowlisting is more secure but requires static egress IPs from the scraper's host.

Some proxy providers embed session and geo-targeting parameters in the username field: `username-session-abcd1234-country-us` routes the session through a US IP and maintains the same exit IP for the duration of the session. This username parameter syntax varies by provider but achieves session stickiness without separate API calls.

Proxy authentication failures return a 407 Proxy Authentication Required status, distinct from a 403 from the target site. Scrapers must handle 407 explicitly — typically by refreshing credentials or checking that the proxy pool configuration is correct.

### What is Proxy Authentication?

Proxy authentication is the process of presenting credentials (username and password) to a proxy server to authorise its use for forwarding scraping requests.

### How does AlterLab handle Proxy Authentication?

Proxy authentication failures return a 407 Proxy Authentication Required status, distinct from a 403 from the target site. Scrapers must handle 407 explicitly — typically by refreshing credentials or checking that the proxy pool configuration is correct.

## Examples

```
import requests

proxies = {
    "http": "http://user:pass@proxy.example.com:8080",
    "https": "http://user:pass@proxy.example.com:8080",
}
response = requests.get("https://target.com", proxies=proxies)
```

## Related Terms

[Proxy PoolA managed collection of proxy IP addresses used to distribute outbound requests across multiple origins and stay below per-IP rate limits.](https://alterlab.io/glossary/proxy-pool)[Rotating ProxyA proxy configuration that automatically assigns a different IP address for each request or at a set interval to prevent IP-based rate limiting.](https://alterlab.io/glossary/rotating-proxy)[Residential ProxyAn IP address assigned by an ISP to a real residential device, used to route scraping requests through genuine consumer IPs.](https://alterlab.io/glossary/residential-proxy)[API AuthenticationThe mechanisms used to verify the identity of callers making requests to an API, typically via API keys, OAuth tokens, or JWT.](https://alterlab.io/glossary/api-authentication)[Session ManagementThe handling of cookies, authentication tokens, and browser state across multiple requests to maintain a continuous browsing session.](https://alterlab.io/glossary/session-management)

## Extract Proxy Authentication data from any website

AlterLab returns clean, structured data from any public URL — no scraper infrastructure needed. Start free, no credit card required.

[View API docs](https://alterlab.io/docs/api/rest)

[Back to Glossary](https://alterlab.io/glossary)