comScore ScorecardResearch
741,333 websites

comScore ScorecardResearch is free to use

http://www.fullcirclestudies.com/scorecardresearch.aspx

ScorecardResearch is service of Full Circle Studies, Inc., is part of the comScore, Inc. market research community, a leading global market research effort that studies and reports on Internet trends and behavior. Here are all the websit...

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Optimizely
162,903 websites

Optimizely offers both free and paid options

http://www.optimizely.com/

Simple, fast, and powerful. Optimizely is a dramatically easier way for you to improve your website through A/B testing. Create an experiment in minutes with our easy-to-use visual interface with absolutely no coding or engineering required...

Market Share by Top Websites

1 comScore ScorecardResearch is leading in Top 10K Sites, Top 100K Sites, Top 1M Sites and The Entire Web.

2 In terms of market share, Optimizely is clearly lagging behind, losing to comScore ScorecardResearch in all segments.

Websites Categories

1 comScore ScorecardResearch has better usage coverage in more websites categories. Including Arts & Entertainment, Games, Adult, Lifestyle and 19 other categories.

2 Optimizely is leading in Business & Consumer Services.

Geography

1 comScore ScorecardResearch is leading in most countries, including United States, Russia, France, Canada and 157 other countries.

2 Optimizely is leading in Syrian Arab Republic, Mali and Republic Of The Congo.