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Optimizely in Homepage Source

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.

Stored source examples for Optimizely

These examples matched cdn.optimizely.com in stored homepage source when the query was sampled on 2026-10-14. The sites may have changed since the source was captured. A match establishes a source reference; it does not confirm an active installation or code execution.

• 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 ...!-- Load Optimizely Project Script -->\n<script src="https://cdn.optimizely.com/js/24657440063.js"></script>\n\n<script>\n// OneTrust Consent ...
• www.hootsuite.com ...=""/><link rel="preconnect" href="https://a4894383279964160.cdn.optimizely.com" crossorigin="anonymous"/><link rel="preload" href="/_next/...
• www.imperva.com ...pe="text/plain" class="optanon-category-C0002" src="https://cdn.optimizely.com/js/6931781924.js"></script>\r\n<!-- Optimizely script for ww...
• 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 ...2JZGYw" async=""></script><link rel="preload" href="https://cdn.optimizely.com/js/26942930964.js" as="script"/><link rel="preload" href="h...
• www.typeform.com ... }\n\n var OPTIMIZELY_SRC =\n "https://cdn.optimizely.com/js/6084697625722880.js";\n var ANALYTICS_GROUP_IDS = ...
• 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 ...d958.min.js" 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 ...

Showing 30 checked source examples. The headline is estimated matches. Open the full ranked list, inspect the matched source, and export the domain list →

Related technologies

How this works

The headline distinguishes candidate upper bounds (index prefilter), estimated matches (a projection from checked samples) and verified matches (an exact count established by the engine). The index contains 131,219,565 homepage documents, one homepage per hostname, including subdomains. The source index was promoted 2026-09-22 and follows a quarterly rebuild schedule. The sample date is when this query was checked against the stored index, not a new crawl of each example site.

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