How to Build a Scraper That Does Not Get Blocked
Short answer: a scraper stays unblocked when it looks like many ordinary users. That means rotating high trust IPs, realistic headers, human like pacing, correct session handling, and graceful backoff. No single trick does it; the combination does.
1. Use the right proxies
Datacenter IPs get blocked fastest on defended sites. Use rotating residential proxies so each request comes from a different real IP, and pick the right country for localized data. ShiftProxies residential proxies cover 195 plus countries with rotating sessions at dashboard.shiftproxies.com.
2. Send realistic headers
Set a normal user agent, accept and accept language headers, and keep cookies within a session. Avoid sending the exact same fingerprint on every request. Small natural variety helps you blend in.
3. Pace your requests
Add randomized delays and keep per IP volume modest. A slower steady crawl that finishes beats a fast burst that gets blocked in minutes.
4. Handle sessions correctly
Rotate IPs for independent page fetches, but use a sticky session for anything stateful like a login or a multi step form. Changing IP mid session is a common block trigger.
5. Render JavaScript when needed
Many sites need JavaScript to load content or pass checks. A headless real browser handles these far better than a plain HTTP client.
6. Retry and back off
- Set timeouts so a slow proxy does not hang the crawler.
- On a block, captcha or 429, rotate to a fresh IP and wait before retrying.
- Never retry aggressively on the same IP.
- Log failed URLs to rerun later.
7. Respect the target
Crawl only public data at a reasonable rate, honor robots guidance where appropriate, and avoid overloading small sites. Polite scraping is safer and more sustainable.
Summary
Rotating residential IPs, realistic headers, randomized pacing, correct session use, JavaScript rendering where needed, and graceful backoff together keep a scraper running. Build all of them in from the start.