What are HTTP status codes in web scraping?

HTTP status codes are three-digit server responses indicating whether requests succeeded or failed. Scrapers use these codes to determine if pages loaded successfully (200), require following redirects (301, 302), are blocked or missing (403, 404), or encountered server errors (500, 503). Understanding status codes helps scrapers handle errors gracefully, retry appropriate requests, and avoid wasting resources on permanently unavailable content.

HTTP status codes are standardized responses that web servers send to indicate the outcome of client requests. When scrapers request pages, servers respond with three-digit codes grouped into five categories. Each category signals different outcomes requiring different scraper behaviors.

Status codes appear in response headers before any content data. Scrapers check these codes to decide whether to process returned content, follow redirects, retry requests, or mark URLs as failed. Proper status code handling prevents scrapers from processing error pages as valid data or repeatedly requesting unavailable resources.

Success codes indicate scrapers received valid content. The most common, 200 OK, means the request worked and content is ready for extraction. Scrapers process the response body and extract data when receiving 200 responses.

Redirection codes tell scrapers content moved to different URLs. 301 Moved Permanently signals permanent relocation requiring scrapers to update stored URLs. 302 Found indicates temporary moves where scrapers should continue using original URLs for future requests. Redirect handling becomes critical when chains exceed reasonable limits.

Client error codes mean requests failed due to client-side issues. 403 Forbidden indicates the server blocks access, often signaling anti-bot detection. 404 Not Found means pages do not exist, requiring scrapers to remove URLs from crawl queues. 429 Too Many Requests signals rate limiting violations demanding slower request rates.

Server error codes indicate temporary server problems. 500 Internal Server Error and 503 Service Unavailable suggest transient issues warranting retry attempts. Unlike 404 errors, server errors do not mean content is permanently gone. Scrapers implement exponential backoff when encountering 5xx codes to avoid overwhelming struggling servers.

The 200 OK code represents successful data retrieval. Scrapers receiving 200 should verify the response body contains expected content rather than error messages. Some servers return 200 with error pages, creating soft 404 situations where status codes lie about actual outcomes.

The 403 Forbidden code often signals anti-scraping mechanisms detected the scraper. This code means the server understood the request but refuses to fulfill it. Scrapers encountering 403 should rotate IPs, adjust user agents, or implement stealth techniques before retrying.

The 429 Too Many Requests code enforces rate limiting. Scrapers hitting 429 must slow down request rates immediately. Ignoring 429 responses leads to IP bans and longer access restrictions. Implementing polite crawling practices prevents triggering 429 responses.

The 503 Service Unavailable code indicates temporary server overload or maintenance. Scrapers should pause and retry after waiting periods. Continuing to hammer servers returning 503 demonstrates poor scraper citizenship and risks permanent blocking.

Configure retry logic based on status code categories. Success codes need no retry. Redirection codes require following location headers. Client errors except 429 should not retry, permanent failures waste resources. Server errors and 429 warrant retry with increasing delays between attempts.

Log all non-200 status codes for monitoring scraper health. Patterns in status codes reveal issues like broken URLs (consistent 404s), blocked IPs (frequent 403s), or aggressive scraping triggering rate limits (429s). Status code analytics guide scraper optimization and target site relationship management.

Implement status-specific error handling rather than treating all failures identically. A 404 means removing a URL from the crawl queue. A 503 means scheduling a retry. A 403 might mean rotating proxies or adjusting request headers. Generic error handling misses opportunities to adapt scraper behavior appropriately.

HTTP status codes communicate request outcomes through three-digit responses grouped into five categories covering success, redirection, client errors, and server errors. Scrapers use these codes to determine appropriate actions including processing content, following redirects, retrying with backoff, or abandoning requests.

Critical codes for web scraping include 200 for success, 403 for blocking, 404 for missing content, 429 for rate limiting, and 503 for temporary unavailability. Each requires different handling strategies from processing data to implementing retry logic with exponential backoff.

Proper status code handling prevents wasting resources on failed requests, enables graceful error recovery, and helps identify scraper issues through code pattern analysis. Logging and monitoring status codes provides insights into scraper health, target site behavior, and anti-bot detection effectiveness.

Learn more: HTTP Status Codes Reference, Google Search and HTTP Status Codes