Why Web Scraping Isn’t Illegal—Legal Risks, Ethics, and Best Practices

When We Talk About Crawlers

Most Python hobbyists think that using requests.get or selenium to fetch a page is a crawler, but real crawlers involve anti‑scraping, reverse engineering, captcha handling, distributed scheduling, and more; simple requests are merely high‑frequency simulated requests.

Robots.txt Protocol

The robots file is a gentleman’s agreement rather than a technical barrier. Many sites, such as Douban, disallow all user‑agents and block paths like /search, making it impossible to scrape anything if you follow it strictly.

Beyond robots.txt, most websites embed crawling restrictions in their user service agreements, reserving the right to sue even if you only make occasional requests.

Data Concerns

Scraping public data for personal use is generally acceptable, but selling or profiting from scraped data is illegal. Privacy‑sensitive information such as phone numbers, ID numbers, or social security data must never be collected, and bulk or unlimited scraping of any data can attract legal trouble.

Non‑public data—backend data, permission‑protected data, or paid‑only data—should never be obtained via crawling.

Restraint

If a site detects your crawler through anti‑scraping measures or bans your IP due to high request frequency, you must throttle requests, respect rate limits, and avoid disrupting the site’s normal business.

Even after bypassing anti‑scraping defenses, do not publicly expose the target site; doing so can lead to cease‑and‑desist letters or lawsuits.

Supplement

When building a crawler for someone else, verify that the request does not infringe on rights and that the client will not use the data for illegal purposes.

Conclusion

Crawlers are not inherently illegal; most failures stem from misuse of data or ignoring site policies. Write code responsibly, respect robots.txt and service agreements, and treat data collection with caution and professionalism.