Website-specific crawlers, or software that crawls one particular website at a time, are great for analyzing your own website's SEO strengths and weaknesses; they're arguably even more useful for scoping out the competition's. Website crawlers analyze a website's URL, link structure, images, CSS scripting, associated apps, and third-party services to evaluate SEO. Not unlike how a website monitoring tool scans for a webpage's overall "health," website crawlers can identify factors such as broken links and errors, website lag, and content or metadata with low keyword density and SEO value, while mapping a website's architecture. Website crawlers can help your business improve website user experience (UX) while identifying key areas of improvement to help pages rank better. DeepCrawl is, by far, the most granular and detailed website crawler in this roundup, although Ahrefs and Majestic also provide comprehensive domain crawling and website optimization recommendations. Another major crawler we didn't test is Screaming Frog, which we'll soon discuss in the section called "The Enterprise Tier."

You may not want certain pages of your site crawled because they might not be useful to users if found in a search engine's search results. If you do want to prevent search engines from crawling your pages, Google Search Console has a friendly robots.txt generator to help you create this file. Note that if your site uses subdomains and you wish to have certain pages not crawled on a particular subdomain, you'll have to create a separate robots.txt file for that subdomain. For more information on robots.txt, we suggest this Webmaster Help Center guide on using robots.txt files13.
Search engines may penalize sites they discover using black or grey hat methods, either by reducing their rankings or eliminating their listings from their databases altogether. Such penalties can be applied either automatically by the search engines' algorithms, or by a manual site review. One example was the February 2006 Google removal of both BMW Germany and Ricoh Germany for use of deceptive practices.[54] Both companies, however, quickly apologized, fixed the offending pages, and were restored to Google's search engine results page.[55]
Webmasters and content providers began optimizing websites for search engines in the mid-1990s, as the first search engines were cataloging the early Web. Initially, all webmasters only needed to submit the address of a page, or URL, to the various engines which would send a "spider" to "crawl" that page, extract links to other pages from it, and return information found on the page to be indexed.[5] The process involves a search engine spider downloading a page and storing it on the search engine's own server. A second program, known as an indexer, extracts information about the page, such as the words it contains, where they are located, and any weight for specific words, as well as all links the page contains. All of this information is then placed into a scheduler for crawling at a later date.
The third type of crawling tool that we touched upon during testing is backlink tracking. Backlinks are one of the building blocks of good SEO. Analyzing the quality of your website's inbound backlinks and how they're feeding into your domain architecture can give your SEO team insight into everything from your website's strongest and weakest pages to search visibility on particular keywords against competing brands.
Depending on your topic / vertical and your geographic location the search engines may have vastly different search volumes. The tool can only possibly offer approximations. Exact search volumes are hard to find due to vanity searches, click bots, rank checkers, and other forms of automated traffic. Exceptionally valuable search terms may show far greater volume than they actually have due to various competitive commercial forces inflating search volumes due to automated search traffic.
Crawlers are largely a separate product category. There is some overlap with the self-service keyword tools (Ahrefs, for instance, does both), but crawling is another important piece of the puzzle. We tested several tools with these capabilities either as their express purpose or as features within a larger platform. Ahrefs, DeepCrawl, Majestic, and LinkResearchTools are all primarily focused on crawling and backlink tracking, the inbound links coming to your site from another website. Moz Pro, SpyFu, SEMrush, and AWR Cloud all include domain crawling or backlink tracking features as part of their SEO arsenals.
When Googlebot crawls a page, it should see the page the same way an average user does15. For optimal rendering and indexing, always allow Googlebot access to the JavaScript, CSS, and image files used by your website. If your site's robots.txt file disallows crawling of these assets, it directly harms how well our algorithms render and index your content. This can result in suboptimal rankings.
Many blogging software packages automatically nofollow user comments, but those that don't can most likely be manually edited to do this. This advice also goes for other areas of your site that may involve user-generated content, such as guest books, forums, shout-boards, referrer listings, etc. If you're willing to vouch for links added by third parties (for example, if a commenter is trusted on your site), then there's no need to use nofollow on links; however, linking to sites that Google considers spammy can affect the reputation of your own site. The Webmaster Help Center has more tips on avoiding comment spam40, for example by using CAPTCHAs and turning on comment moderation.

Description meta tags are important because Google might use them as snippets for your pages. Note that we say "might" because Google may choose to use a relevant section of your page's visible text if it does a good job of matching up with a user's query. Adding description meta tags to each of your pages is always a good practice in case Google cannot find a good selection of text to use in the snippet. The Webmaster Central Blog has informative posts on improving snippets with better description meta tags18 and better snippets for your users19. We also have a handy Help Center article on how to create good titles and snippets20.

WooRank is a freemium tool that provides an “instant website review.” Without a premium account, you are only allowed to generate a limited number of free reports, but you are able to view previously generated reports. Also, the tool currently offers a 7-day unlimited free trial, which gives you access to unlimited reviews. If you’re interested in purchasing a plan, the cheapest one is $49/month.

As an Internet marketing strategy, SEO considers how search engines work, the computer-programmed algorithms that dictate search engine behavior, what people search for, the actual search terms or keywords typed into search engines, and which search engines are preferred by their targeted audience. SEO is performed because a website will receive more visitors from a search engine the higher the website ranks in the search engine results page (SERP). These visitors can then be converted into customers.[4]