Crawlability and indexing are steps in most search engine’s process of gathering information and presenting it as search results. Crawlability refers to the search engine’s ability to access the content on a page. A crawlable site lets search engine bots carry out their basic tasks: discover that a page exists through links pointing to it, reach a page from main site entry points (such as the home page), examine the contents of the page, and find links to other pages.
On the other hand, indexability refers to the different parameters and signals that tell a search engine whether the content should be included in the index of rankable pages.
Using an SEO crawler helps you understand how a search engine looks at your website. With Oncrawl, for example, you can not only find dashboards on which parts of your site are indexable and which are not–and why–, but you can also spot crawl errors, and dig deep into the relationships between technical factors, indexing, and ultimately ranking.