1. GoogleBot

It is a web crawler that systematically browses the internet, gathering information about websites and updating Google's search index.

2. BingBot

It is used by Bing to crawl and index web pages, providing data for Bing's search engine.

3. BaiduSpider

It is used by Baidu, the largest search engine in China, to crawl and index web pages.

4. YandexBot

Used by Yandex, the largest search engine in Russia, it functions similarly to other web spiders, exploring the internet and gathering information.

5. DuckDuckBot

It is a privacy-focused crawls and indexes web pages, collecting information for DuckDuckGo's search results.

6. MJ12Bot

It is SEO and backlink analysis tool that provides insights to improve a website's search engine rankings.

7. AhrefsBot

It crawls and indexes web pages to collect data on backlinks and other SEO metrics.

8. SEMrushBot

It is used by SEMrush, a digital marketing tool that offers SEO, PPC, and content marketing solutions

9. Screaming Frog SEO Spider 

It is a desktop application for website crawling and auditing, such as broken links or duplicate content.