Optiverse
A simple guide to A/B testing
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Occam's Razor by Avinash Kaushik
Best practice in benching performance using analytics. Includes easy to understand ROI models.
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Nibbler
Tests and scores any website out of 10 for accessibility, SEO, social media and technology. Useful for comparing competitors.
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Spyfu
Download your competitors' most profitable keywords and ads for paid & organic search.
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Quantcast
For websites you don't own, get a view of a website's audience demographics and interests.
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Simply Measured Social Media Analytics Tools
Get sample reports on a brand's followers/audience, from interests to influence. Available on Facebook, Twitter, Instagram, LinkedIn, Google+, and Vine.
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FollowerWonk
Find customers interested in your brand with the 'search bios' function. Alternatively, find people by interests. Compare two brands on Twitter.
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http://keywordtool.io
Quickly find out what your audience is searching for on Google, Bing, and YouTube. Useful for PPC, SEO, and content creation.
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Similar Web
For websites you don't own, use this website analytics tool to get a traffic overview, including: monthly visits, traffic sources, geography, referring sites, and audience interests.
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Twitter Analytics
Get reliable impression and engagement rates of tweets from brands
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EpicBeat
Find trends and content that's being shared the most for any topic or website.
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Brand impressions by Think with Google
Easily compare brands' online activity now & over time.
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QuickSprout
Get a quick analysis of how a website is gaining traffic, based on effectiveness of content, SEO and user experience. Compare up to three competitors.
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