At a high level, rock-solid, "white hat" SEO basics don't vary widely. Create great content that viewers will want to link to via social media, blogs or other online sites. Make sure your content is easy to find with relevant keywords. Ensure that your website has no technical issues that could prevent search engines from indexing its content.But how exactly do you do this\u2014and how do you measure success? That's where search engine optimization (SEO) tools come in.The following 20 SEO tools, listed in no particular order, come recommended by three experts:Jill Whalen, SEO Consultant at High Rankings\nNicole Munoz, CEO and founder of StartRankingNow, who recently offered a session on her favorite tools at the Online Marketing Summit in Santa Clara, Calif.\nMatt McGee, editor-in-chief of Search Engine Land and Marketing LandSEO Tools From Google\n\n1. Google AdWords Keywords Tool \n\nGoogle's free keyword tool is designed for those who write ads that run on Google's search engine results pages, in Gmail and on other affiliated sites. It provides information such as the domestic and international search volume for a given keyword phrase, how competitive the phrase is and related keywords. Google's tool is highly useful for any Web content developer, and it's one of the tools most SEO experts use regularly. "It's pretty much the only tool I use or recommend for doing keyword research," Whalen says.\n\n2. Google Analytics\n\nMcGee, Munoz, Whalen and many other SEO experts rely on Google's free site analytics tool. Whalen calls it "the most critical tool of all" because it helps you figure out why a site has lost\u2014or gained\u2014traffic. Google Analytics enables any website manager to see the keywords used to bring visitors to the site, the bounce rate for each site page, visitor demographics and lots more. \n\nTips: 5 Ways IT Can Get More From Google Analytics\nRelated: Google Integrating Analytics, SEO Tools\n\n3. Google Webmaster Tools\n\nGoogle Webmaster Tools, another essential and free toolset, helps you diagnose website crawl errors and perform other tasks to improve your site's "health." Though it's not particularly difficult to use, those without much website management experience may be a bit confused. \n\n4. Google YouTube Keyword Tool\n\nYouTube videos can rank highly in Google searches when they're optimized with the appropriate keywords. Munoz recommends using this tool to find keywords that will help your YouTube videos rank in Google searches as well as in YouTube searches. \n\n5. Google Suggest\n\nWhenever you begin typing a keyword phrase in a Google search box, Google suggests related phrases based on your own search history as well as terms popular with other users. A quick way to get keyword ideas, then, is to simply start typing a phrase in Google to see what the search engine suggests, Munoz says.Third-Party SEO Tools\n\n6. Screaming Frog SEO Spider \n\nScreaming Frog's SEO Spider is a desktop program that sends a "spider" (or crawler) to a site and compiles a spreadsheet-like report on the pages it crawls. You'll see title tags, URLs, meta descriptions, meta keywords and H1 tags, as well as pages that might have 404 errors. Whalen uses the program whenever starting a new site review. "It helps me get an overall feel for the site and quickly shows me any major technical issues," she says. The basic program is free; the licensed version adds more features for \u00a399 (about $150 U.S.) per year.7. SpyFu\n\nMunoz recommends SpyFu, a keyword research tool that provides useful intelligence on the keywords your competitors are bidding on and\/or using to rank in organic searches. The service costs $79 per month. \n\n\n\n8. Browseo\n\nBrowseo (a mashup of the words "browse" and "SEO") helps you quickly determine a page's structure, as well as its relevance for specific keyword phrases. It's a fast way to get a helpful breakdown of a particular web page, Munoz says. \n\n9. WebSite Auditor\n\nMunoz recommends this software, available for Windows, Mac, and Linux operating systems, to analyze website content and help optimize each page for a particular keyword. It's available in free and paid versions\u2014the latter of which, depending upon features, are $99.75 and $249.75. \n\nAnalysis: Why Your Company Should Hire a Dedicated SEO Specialist\nTips: Top 10 Things to Look for in an SEO Expert\n\n10. Copyscape\n\nThis Web-based tool will tell you all the places on the Internet where you may have duplicate content. Munoz says it's good for finding out if other sites have copied your content, too.\n\n11. Rex Swain's HTTP Header Viewer\n\nWhalen uses this free tool to discover if a Web page has any type of redirects, adding that, "for SEO purposes, we like to see 301 redirects rather than 302s or any other kind." \n\n12. Ahrefs Site Explorer\n \nEnter a URL and Ahrefs's Site Explorer tool will show you its backlinks, or external links from other sites. "You can get a lot of that information also from Google Webmaster Tools these days, but I'll often find different ones showing up in Ahrefs that I may not have seen in Google Webmaster," Whalen notes. "I mainly use it to check if the website I'm reviewing has a lot of spammy links," which can cause a site to be significantly demoted in Google rankings. Google Chrome Extensions\n\n13. NoFollow\n\nGoogle Chrome (as well as Mozilla Firefox) has a number of free extensions and add-ons designed to help with SEO. Whalen calls this "the best extension ever" for SEO consultants. "It outlines all links on a page that have the nofollow attribute on it. But even better is that it pops up a little window if the page you're looking at has a noindex tag on it," she says. "You wouldn't believe how many websites I find through this extension that are inadvertently blocking all search engines from being able to index them."\n\n14. PageRank Status\n\nWith this free extension, you can quickly learn about a webpage, such as its PageRank, Alexa traffic ranking, backlinks and number of pages indexed by various search engines.\n\n15. TagAssistant\n\nThe free TagAssistant reveals Google Analytics code errors on a website page. Whalen says this can come in handy when a site appears to have lost traffic. "Sometimes you'll find that the page didn't have the Google Analytics code, or it was on [the page] incorrectly."\n\n16. Awesome Screenshot\n\nWhalen uses this free screenshot utility when performing SEO site audits. Because Awesome Screenshot lets you add arrows, circles and text, the tool makes it easy to capture a screenshot of a Web page and visually show a client where the trouble spots are. Once she captures the screenshots, she pastes them into Evernote, along with other notes about a site's SEO issues, and uses those notes to compile a report.Content Creation Tools\n\n17. Quora \n\nQuora is a popular question-and-answer website McGee says he finds useful in developing blog topics. "A single topic can lead to several new ideas for blog content," he says. "Just browsing the questions for any given topic is great, but then reading the answers and discussions on certain questions is even better. It can also help you identify experts on certain topics that you may want to interview for articles. And there really is a solid variety of content there. It's long since stopped being just a mecca for tech-related Q&A."\n\n18. InboxQ\n\nInboxQ is an online tool as well as a Google Chrome and Mozilla Firefox extension. Type a simple keyword phrase and InboxQ will show the questions Twitter users are asking on that topic. Munoz uses this tool to generate topics for blogs and other online content. (The more a topic is being discussed in Twitter, the more likely new, optimized content on that topic will attract interest and, by extension, get social shares and links, which can help boost search engine rankings.)\n\n19. WordPress.org\n\nGoogle loves, and tends to reward, fresh content with higher search rankings. Blogging, of course, is an easy way to create that content. WordPress.org is the blogging platform many SEO experts use because, once you've set up the blog (which can admittedly be tricky) and found a Web host, it's simple. There are also countless free plug-ins to help you optimize each blog post, such as WordPress SEO and All in One SEO.How-to: 5 Steps to Enhance Your WordPress Online Business Site and Improve Your WordPress Site and Increase Sales With OptimizePress(Note: A WordPress.com blog isn't the same as one built with WordPress.org's open-source blogging platform. One notable difference is the former's lack of SEO plug-ins.)\n\n20. HootSuite\n\nOnce your latest blog post goes live, it's time to publicize it on social media to attract traffic (and potential links). HootSuite is a social media dashboard that lets you schedule and simultaneously post updates to Twitter, LinkedIn, Facebook, Google+ and other social media networks. HootSuite offers free as well as paid plans (starting at $10\/month). Some SEO experts also like Buffer, a similar service that posts to Facebook, Twitter, LinkedIn and App.net accounts.James A. Martin is an SEO and social media consultant and writes the CIO.com Martin on Mobile Apps blog. Follow him on Twitter. Follow everything from CIO.com on Twitter @CIOonline, on Facebook, and on Google +.