Third-Party Script Prevalence on Alexa Top 50
Since beefing up my technique for itemizing third-party requests, I’ve been looking into which third-party domains and services are most prevalent. Starting with a spreadsheet of the top 50 US sites (according to Alexa in late December 2017), I downloaded and analyzed HAR files for each. Caveats:
- Results (# of requests) may change as sites are updated.
- I chose to start with US sites because of my own familiarity.
- 46 sites actually (3 NSFW sites not tested and t.co doesn’t apply)
After a few grunt work sessions, I have a spreadsheet that cross-references those top 46 sites with the domains from which third-party requests originate. I’ll spare you the entire spreadsheet, but some initial points of interests below:
- The top 46 US sites made requests from 213 different domains.
- CDN-related request domains are included.
- 75 of those different domains are unique to 1 site.
- Third-party serving domains are prevalent. Here are domains that appear on the 46 sites tested more than 10 times:
| Third-party domain | # of top 46 sites | % of top 46 sites |
|---|---|---|
| doubleclick.net | 38 | 82.6% |
| facebook.com | 32 | 69.6% |
| google-analytics.com | 27 | 58.7% |
| googlesyndication.com | 25 | 54.3% |
| googleadservices.com | 24 | 52.2% |
| cloudfront.net | 20 | 43.5% |
| googleapis.com | 20 | 43.5% |
| scorecardresearch.com | 18 | 39.1% |
| 2mdn.net | 17 | 37.0% |
| adnxs.com | 17 | 37.0% |
| fastly.net | 17 | 37.0% |
| akamaihd.net | 16 | 34.8% |
| amazonaws.com | 16 | 34.8% |
| demdex.net | 15 | 32.6% |
| googletagservices.com | 15 | 32.6% |
| adsrvr.org | 14 | 30.4% |
| fonts.googleapis.com | 14 | 30.4% |
| bing.com | 13 | 28.3% |
| connect.facebook.net | 13 | 28.3% |
| fbcdn.net | 12 | 26.1% |
| quantserve.com | 12 | 26.1% |
| truste.com | 12 | 26.1% |
| adsafeprotected.com | 11 | 23.9% |
| amazon-adsystem.com | 11 | 23.9% |
| analytics.twitter.com | 11 | 23.9% |
| bluekai.com | 11 | 23.9% |
| jquery.com | 11 | 23.9% |
| rlcdn.com | 11 | 23.9% |
| rubiconproject.com | 11 | 23.9% |
| serving-sys.com | 11 | 23.9% |
| turn.com | 11 | 23.9% |
| moatads.com | 10 | 21.7% |
Here are the number of unique third-party domains from which requests originate (excluding multiple requests from the same domain) per top 46 site:
| Site | # of third-party domains |
|---|---|
| nytimes.com | 64 |
| washingtonpost.com | 63 |
| Metropcs.mobi | 59 |
| cnn.com | 57 |
| ebay.com | 49 |
| msn.com | 45 |
| microsoft.com | 43 |
| wikia.com | 42 |
| salesforce.com | 40 |
| bestbuy.com | 38 |
| imdb.com | 37 |
| twitch.tv | 37 |
| espn.com | 36 |
| wordpress.com | 32 |
| target.com | 29 |
| diply.com | 28 |
| reddit.com | 28 |
| amazon.com | 27 |
| walmart.com | 23 |
| stackoverflow.com | 21 |
| etsy.com | 19 |
| pinterest.com | 19 |
| paypal.com | 18 |
| imgur.com | 13 |
| twitter.com | 13 |
| chase.com | 12 |
| youtube.com | 12 |
| linkedin.com | 11 |
| yahoo.com | 11 |
| yelp.com | 11 |
| tumblr.com | 10 |
| bankofamerica.com | 9 |
| (outlook) live.com | 9 |
| netflix.com | 8 |
| office.com | 7 |
| facebook.com | 6 |
| google.com | 6 |
| blogspot.com | 5 |
| bing.com | 4 |
| github.com | 4 |
| instagram.com | 4 |
| microsoftonline.com | 4 |
| wellsfargo.com | 3 |
| apple.com | 2 |
| craigslist.org | 2 |
| wikipedia.org | 1 |
I don’t have much commentary at this point—some numbers are higher or lower than expected, and it’s understandable why some sites have more than others. Heck, with video or tweet embeds my site can pull 10+ third-domains surprisingly easy. I need more context, so perhaps it’d be logical to run more tests around a single category.
Next, I’ll be researching the more prevalent third-party services. Many of them are new to me. Further down the road, I’ll look at performance impact, but that’s a whole ’nother ball of wax.