Types of Crawler

How many types of Crawler available nowadays ?

There are so many number of crawlers available in the market but let me list few.
Botify is one of the cloud based crawler and it has clients Airbnb and Dailymotion.
Deepcrawl is another cloud based crawler which uses JavaScript rendering.
We can integrate it with Google analytics.

Ryte is a web based crawler and it's used along with screaming frog and deep crawl.

If you search for a keyword "Salesforce interview questions" then these crawlers will render results using JavaScript.

There are many - ScreamingFrog, Xenu, Deep crawl, Oncrawl etc.

Out of the above, Oncrawl is one of the best, however its pretty expensive, so not sure if its suitable for smaller websites.