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Websites Using Optimizely

Optimizely runs A/B tests, feature flags and personalization. Its snippet loads synchronously in the head so variations apply before first paint and avoid a content flash.

The source-code fingerprint

The experimentation snippet is fetched from cdn.optimizely.com/js/<projectId>.js, carrying the account's numeric project ID in the path.

Likely false positives: The loader is present whether or not a test is currently live, and covers both the legacy Web Experimentation and newer snippets; it does not reveal which experiments run.

Example websites using Optimizely

These domains all contain the cdn.optimizely.com fingerprint in their homepage source right now. A match is a verified substring of the live page, so confidence is high, the false positives noted above are the main caveat.

• www.npr.org ...rg"};\n</script>\n<script type="text/javascript" src="https://cdn.optimizely.com/js/11107397707.js">\n </script>\n<script type="text/javascr...
• www.tandfonline.com ...replaceState(null,null," ");\n</script>\n<script src="https://cdn.optimizely.com/js/24511550181.js" nonce="9536e0603f3f2fdf-SJC"></script>\n<...
• calendly.com ...ipt\n defer="defer"\n \tsrc="https://cdn.optimizely.com/js/19947277778.js"\n \ttype="text/javascript"\n ...
• www.cnn.com ...cripttemplates/otSDKStub.js","OPTIMIZELY_BASE_SRC":"https://cdn.optimizely.com/public/125375509/s/","OPTIMIZELY_ENV":"prod","MARKETS_QUOTE...
• www.kickstarter.com ....card .hdr { display: none }\n</style>\n\n<script src="https://cdn.optimizely.com/js/14948670400.js"></script>\n<script>\n window.OPTIMIZELY_D...
• mailchimp.com ...= false </script>\n\n \n <script src="https://cdn.optimizely.com/js/8896740779.js" type="text/plain" class="optanon-category...
• edition.cnn.com ...cripttemplates/otSDKStub.js","OPTIMIZELY_BASE_SRC":"https://cdn.optimizely.com/public/125375509/s/","OPTIMIZELY_ENV":"prod","MARKETS_QUOTE...
• zapier.com ...ogletagmanager.com" rel="dns-prefetch"/><link href="https://cdn.optimizely.com" rel="preconnect"/><link href="https://cdn.optimizely.com" ...
• bitly.com ...ext/javascript" class="optanon-category-C0001" src="https://cdn.optimizely.com/js/16488430484.js"></script><link href="https://mkt-static....
• www.constantcontact.com ...c8c.js" async=""></script><link rel="preload" href="https://cdn.optimizely.com/js/21006071257.js" as="script"/><link rel="preload" as="ima...
• asana.com ...ment.createElement("script")).src="production"===e?"https://cdn.optimizely.com/js/4851607934861312.js":"https://cdn.optimizely.com/js/5324...
• www.getsmarter.com ... and GetSmarter</title>\n <link rel="preload" href="https://cdn.optimizely.com/js/6010650745372672.js" as="script" crossorigin>\n <link re...
• www.tableau.com ...ge Builder"},"optimizely":{"enabled":true,"cdnUrl":"https://cdn.optimizely.com/js/25742810060.js"},"iisVersion":"v1-stable","locale":"en-u...
• www.foxbusiness.com ...href="//log.outbrain.com">\n<link rel="dns-prefetch" href="//cdn.optimizely.com">\n<link rel="dns-prefetch" href="//b.scorecardresearch.com"...
• www.elastic.co ..." data-next-head=""/><link rel="dns-prefetch" href="https://cdn.optimizely.com" data-next-head=""/><link rel="dns-prefetch" href="https://...
• www.elsevier.com ...et" data-next-head=""/><link rel="preconnect" href="https://cdn.optimizely.com" data-next-head=""/><link rel="icon" href="/images/elsevier...
• www.starbucks.com ...zed"});\n })();\n </script><script src="https://cdn.optimizely.com/js/13849340212.js"></script><link rel="stylesheet" href="/_...
• www.shipstation.com ...ogletagmanager.com' />\n<link rel='preconnect' href='https://cdn.optimizely.com' />\n<link href='https://cdn.jsdelivr.net' crossorigin rel='...
• www.hootsuite.com ...=""/><link rel="preconnect" href="https://a4894383279964160.cdn.optimizely.com" crossorigin="anonymous"/><link rel="preload" href="/_next/...
• www.techtarget.com ...doubleverify.com/"/>\n<link rel="dns-prefetch" href="https://cdn.optimizely.com/"/>\n<link rel="dns-prefetch" href="https://www.googletagman...
• www.computerweekly.com ...doubleverify.com/"/>\n<link rel="dns-prefetch" href="https://cdn.optimizely.com/"/>\n<link rel="dns-prefetch" href="https://www.googletagman...
• www.doctorswithoutborders.org ...5kCNeCm8V3TlXyYDwBbbJp4A" />\n\n \n <script src="https://cdn.optimizely.com/js/25424010304.js"></script>\n <!-- BMSF-942: Pantheon in...
• www.optimizely.com ...8no8kv" async=""></script><link rel="preload" href="https://cdn.optimizely.com/js/26942930964.js" as="script"/><link rel="preload" href="h...
• www.typeform.com .../cdn.jsdelivr.net" />\n\n<link rel="preconnect" href="https://cdn.optimizely.com" />\n<link rel="dns-prefetch" href="https://cdn.optimizely.c...
• www.channel4.com ...4-dtm/latest/dtm.js" async=""></script><script src="https://cdn.optimizely.com/js/8171642667.js"></script><link rel="canonical" href="http...
• mixpanel.com ... })\r\n</script>\r\n\r\n<!-- optimizely -->\r\n<script src="https://cdn.optimizely.com/js/5838709522694144.js"></script>\r\n\r\n<!-- sentry -->\r\n<scri...
• www.heart.org ...imizely script start -->\r\n <script src="https://cdn.optimizely.com/js/25670000279.js"></script>\r\n <!-- Optimizely ...
• my.clevelandclinic.org ...e699346f114" as="script"/><link rel="preload" href="https://cdn.optimizely.com/js/28007920049.js" as="script"/><link rel="preload" href="h...
• www.seattletimes.com ...hpriority='low' /> <link rel="preload" href="https://cdn.optimizely.com/js/25075460524.js" as="script" fetchpriority="low">\n ...
• www.klaviyo.com ...klaviyo.js?company_id=9BX3wh"></script><script src="https://cdn.optimizely.com/js/6209881250725888.js"></script><meta property="og:locale"...

Showing 30 of 56,350 matching sites. Open the full ranked list, inspect the matched source, and export the domain list →

Related technologies

How this works

SearchWebCode indexes the raw HTML, CSS and JavaScript source of public web pages. To find sites using Optimizely we match the literal fingerprint cdn.optimizely.com, the code Optimizely ships, against that index, then verify each match against the raw source. Counts reflect the current index (129,313,463 domains, refreshed monthly, last built August 2026) and grow as we scale toward the whole web. Run the search yourself to see every match, view the full page source for any result, filter by TLD or regex, and export the domain list.

Comparing adoption across tools? The Web Technology Adoption Report ranks the most common tags in the index side by side.