What is robots.txt and why does it matter for web scraping?
Robots.txt is a standard used by websites to communicate with web crawlers about which parts of the site should or shouldn't be accessed.
Purpose:
- Tells bots which pages they can and cannot crawl
- Helps prevent server overload from aggressive crawlers
- Protects sensitive or private sections of websites
- Guides crawlers to important content (via sitemaps)
- Part of the Robots Exclusion Protocol
Location:
Always located at the root of a domain:
https://example.com/robots.txt- NOT
https://example.com/about/robots.txt
Why it matters for scraping:
Legal considerations:
- Respecting robots.txt demonstrates good faith
- Some jurisdictions consider violating robots.txt illegal
- Part of ethical scraping practices
Technical considerations:
- Some sites actively block IPs that ignore robots.txt
- Crawl-delay directives help you avoid being rate-limited
- Sitemap locations help discover all pages efficiently
Ethical considerations:
- Respects website owners' wishes
- Prevents server overload
- Maintains a healthy web ecosystem
Common misconception:
robots.txt is not a security measure. It's a request, not enforcement. However, ignoring it can lead to:
- IP bans
- Legal issues
- Rate limiting
- Damage to reputation
Best practice:
Always check robots.txt before scraping:
- Download and parse robots.txt
- Respect Disallow directives
- Honor Crawl-delay settings
- Use sitemap locations if available
Most legitimate web scraping respects robots.txt while focusing on public data.