What is a proxy?
A proxy is an intermediary server that forwards your crawler’s requests to a website and returns the response back to you. From the website’s perspective, the request appears to come from the proxy’s IP address rather than your own.
Why web crawlers use proxies
Many websites defend against automated access with IP-based rules: rate limits, temporary bans, challenge pages, or outright blocking. Proxies help you distribute request load across multiple outbound IPs and reduce the odds that a single IP gets throttled or burned.
Spread requests across IPs and avoid sending “everything” from one address that gets flagged quickly.
Increase parallelism while keeping per-IP request pacing within reasonable limits.
See what users in different regions see (pricing, availability, language, compliance banners, and more).
Separate crawl workloads by site, project, or risk profile so one target doesn’t impact everything else.
Types of proxies for web scraping
“Proxy” can mean very different things. Choosing the wrong type is one of the fastest ways to waste money and still get blocked.
Fast and cost-effective, but more likely to be flagged on sites that aggressively filter non-residential traffic.
Higher trust for many targets, better for strict anti-bot environments — but usually slower and more expensive.
Often the highest “trust” profile. Useful for extremely strict targets, but can be costly and limited in volume.
Stable identity for long sessions and consistent access. Good for login-based crawling and stateful workflows.
Rotation strategy: per-request vs sticky sessions
Proxy “rotation” isn’t one setting. The right strategy depends on whether your crawler needs continuity (cookies, sessions, carts, logins) or is simply downloading public pages.
Per-request rotation
Use a new IP frequently to distribute load. Best for public pages where session continuity doesn’t matter.
Sticky sessions
Keep the same IP for a window of time so cookies and browsing behavior look consistent (common for strict anti-bot setups).
Workload isolation
Assign a stable subset of IPs per target site or per crawl job to limit “blast radius” when a site gets stricter.
Health checks + cooldown
Track failures, challenge pages, and latency. Temporarily remove IPs that look burned and recycle them later.
Why websites block crawlers (and why proxies aren’t always enough)
Many defenses are not purely “IP lists.” Anti-bot platforms can evaluate request patterns, headers, TLS characteristics, cookie behavior, navigation flow, and abnormal concurrency.
- Rate & burst patterns: too many requests too quickly from any identity.
- Behavior mismatch: no referrers, no cookies, no realistic navigation or session history.
- Fingerprinting: request headers or browser fingerprints that look automated.
- Protected endpoints: aggressive protection on search, add-to-cart, availability, or pricing APIs.
How to use a proxy with a PHP web crawler (cURL)
In PHP, proxies are typically configured via cURL options. Most production crawlers also need timeouts, retries, and (often) proxy authentication.
<?php
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
// Proxy host + port
curl_setopt($ch, CURLOPT_PROXY, $proxyHost);
curl_setopt($ch, CURLOPT_PROXYPORT, $proxyPort);
// Optional: proxy auth (user:pass)
if (!empty($proxyUser) && !empty($proxyPass)) {
curl_setopt($ch, CURLOPT_PROXYUSERPWD, $proxyUser . ":" . $proxyPass);
}
// Reliability basics
curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 10);
curl_setopt($ch, CURLOPT_TIMEOUT, 30);
// If you use cookies / sessions
curl_setopt($ch, CURLOPT_COOKIEJAR, $cookieJarPath);
curl_setopt($ch, CURLOPT_COOKIEFILE, $cookieJarPath);
$html = curl_exec($ch);
$httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
if ($html === false) {
$err = curl_error($ch);
// Log error + mark proxy health down
}
curl_close($ch);
?>Proxy management checklist for long-running crawlers
If you’re collecting data continuously (daily/weekly), the proxy layer becomes infrastructure. These are common upgrades that turn “it works sometimes” into a stable data pipeline.
Track latency, timeout rate, and ban signals so weak IPs don’t poison crawl quality.
Detect 403/429, redirects to challenges, “access denied” HTML, and suspiciously small pages.
Temporarily retire IPs that get flagged and re-test later instead of burning the whole pool.
Different targets often need different proxy types, session strategies, and pacing rules.
Compliance and ethical boundaries
Proxy usage should support legitimate access patterns and responsible data acquisition. The right approach depends on your use case, target sites, and how the data will be used internally.
- Respectful pacing: avoid abusive request volumes that degrade site performance.
- Credential handling: treat login-based crawling as a high-risk workflow that needs careful controls.
- Auditability: log collection behavior so you can debug and explain data lineage.
Questions About Web Crawlers and Proxies
These are common questions teams ask when their web scrapers start getting blocked and they need a reliable proxy strategy.
Do proxies prevent Cloudflare blocks? +
Sometimes — but not always. Many anti-bot systems evaluate more than IP address: request pacing, cookies, headers, session continuity, and behavior patterns. Proxies are often necessary for scale, but durable crawling usually requires a full strategy (rotation, backoff, session handling, and monitoring).
What proxy type is best for web scraping? +
It depends on the target sites. Many projects start with datacenter proxies because they’re fast and cost-effective. If the target is strict, residential proxies with sticky sessions often perform better. Extremely strict environments may require mobile proxies or a more browser-like collection method.
How many proxies do I need? +
The right number depends on your request rate, the strictness of the site, and how aggressively you rotate. A useful way to estimate is to decide a safe per-IP request pace, then size the pool so your total throughput stays below that.
Is rotating proxies always better than a stable IP? +
Not always. Some crawlers do best with stable outbound IPs and careful pacing, especially for long-running, monitored collection. In other scenarios (geo-testing, strict per-IP limits, high throughput), rotation is essential.
Can Potent Pages implement proxy rotation and monitoring? +
Yes. We design and operate crawlers that include proxy routing, health checks, retries/backoff, ban detection, and monitoring — with delivery in the format your team needs.
Want a crawler that doesn’t break every week?
We build durable crawling and extraction systems with monitoring, alerts, and the right proxy/IP strategy for your targets.
