Third Party Web

This document is a summary of which third party scripts are most responsible for excessive JavaScript execution on the web today.

Table of Contents

1. Goals
2. Methodology
3. Data
   1. Summary
   2. How to Interpret
   3. Third Parties by Category
      1. Ads
      2. Analytics
      3. Social
      4. Video
      5. Developer Utilities
      6. Hosting Platforms
      7. Marketing
      8. Customer Success
      9. Content & Publishing
      10. Libraries
      11. Mixed / Other
   4. Third Parties by Total Impact
4. Future Work
5. FAQs
6. Contributing

Goals

1. Quantify the impact of third party scripts on the web.
2. Identify the third party scripts on the web that have the greatest performance cost.
3. Give developers the information they need to make informed decisions about which third parties to include on their sites.
4. Incentivize responsible third party script behavior.

Methodology

HTTP Archive is an inititiave that tracks how the web is built. Twice a month, ~4 million sites are crawled with Lighthouse on mobile. Lighthouse breaks down the total script execution time of each page and attributes the execution to a URL. Using BigQuery, this project aggregates the script execution to the origin-level and assigns each origin to the responsible entity.

Data

Summary

Across top ~1 million sites, ~800 origins account for ~65% of all script execution time with the top 100 entities already accounting for ~59%. Third party script execution is the majority chunk of the web today, and it's important to make informed choices.

How to Interpret

Each entity has a number of data points available.

1. Usage (Total Number of Occurrences) - how many scripts from their origins were included on pages
2. Total Impact (Total Execution Time) - how many seconds were spent executing their scripts across the web
3. Average Impact (Average Execution Time) - on average, how many milliseconds were spent executing each script
4. Category - what type of script is this

Third Parties by Category

This section breaks down third parties by category. The third parties in each category are ranked from first to last based on the average impact of their scripts. Perhaps the most important comparisons lie here. You always need to pick an analytics provider, but at least you can pick the most well-behaved analytics provider.

Overall Breakdown

Unsurprisingly, ads account for the largest identifiable chunk of third party script execution. Other balloons as a category primarily due to Google Tag Manager which is used to deliver scripts in multiple categories. Google Tag Manager script execution alone is responsible for more than half of the "Mixed / Other" category.

Ads

These scripts are part of advertising networks, either serving or measuring.

Rank	Name	Usage	Average Impact
1	Scorecard Research	4,740	90 ms
2	Criteo	63,058	137 ms
3	Taboola	23,818	183 ms
4	AppNexus	16,942	235 ms
5	Yahoo Ads	8,495	247 ms
6	Pubmatic	3,033	255 ms
7	Market GID	3,831	274 ms
8	MGID	10,472	277 ms
9	Integral Ads	23,942	296 ms
10	Google/Doubleclick Ads	1,412,404	330 ms
11	Sizmek	3,831	333 ms
12	Yandex Ads	28,882	386 ms
13	DoubleVerify	4,041	503 ms
14	Moat	23,170	616 ms
15	OpenX	12,505	821 ms
16	MediaVine	9,205	839 ms
17	Media Math	3,498	905 ms
18	33 Across	20,756	1170 ms
19	Popads	6,545	1245 ms
20	WordAds	30,961	2543 ms

Analytics

These scripts measure or track users and their actions. There's a wide range in impact here depending on what's being tracked.

Rank	Name	Usage	Average Impact
1	Alexa	1,721	56 ms
2	Baidu Analytics	8,018	79 ms
3	Mixpanel	7,258	79 ms
4	Google Analytics	1,533,217	79 ms
5	Hotjar	108,933	89 ms
6	Crazy Egg	2,214	91 ms
7	Adobe Analytics	34,436	192 ms
8	Tealium	15,933	214 ms
9	Segment	6,581	228 ms
10	Optimizely	13,853	247 ms
11	Salesforce	40,451	291 ms
12	Histats	15,770	339 ms
13	Yandex Metrica	217,229	377 ms
14	Lucky Orange	6,037	870 ms

Social

These scripts enable social features.

Rank	Name	Usage	Average Impact
1	VK	7,578	61 ms
2	Pinterest	11,122	71 ms
3	Facebook	1,212,567	120 ms
4	Yandex Share	30,677	128 ms
5	Twitter	295,308	154 ms
6	LinkedIn	10,663	156 ms
7	ShareThis	39,884	216 ms
8	AddThis	179,424	254 ms
9	Tumblr	46,800	330 ms
10	PIXNET	53,889	473 ms
11	Disqus	723	580 ms

Video

These scripts enable video player and streaming functionality.

Rank	Name	Usage	Average Impact
1	YouTube	23,184	104 ms
2	Wistia	21,319	254 ms
3	Brightcove	5,133	469 ms

Developer Utilities

These scripts are developer utilities (API clients, site monitoring, fraud detection, etc).

Rank	Name	Usage	Average Impact
1	New Relic	3,613	52 ms
2	Stripe	3,775	66 ms
3	OneSignal	41,178	88 ms
4	Google APIs/SDK	977,712	115 ms
5	App Dynamics	2,248	117 ms
6	Cloudflare	3,151	185 ms
7	PayPal	6,376	241 ms
8	Yandex APIs	57,425	368 ms
9	Distil Networks	11,489	409 ms
10	Sentry	15,272	729 ms

Hosting Platforms

These scripts are from web hosting platforms (WordPress, Wix, Squarespace, etc). Note that in this category, this can sometimes be the entirety of script on the page, and so the "impact" rank might be misleading. In the case of WordPress, this just indicates the libraries hosted and served by WordPress not all sites using self-hosted WordPress.

Rank	Name	Usage	Average Impact
1	WordPress	135,176	113 ms
2	Shopify	227,933	163 ms
3	Squarespace	86,605	412 ms
4	Hatena Blog	53,675	516 ms
5	Wix	158,466	1153 ms

Marketing

These scripts are from marketing tools that add popups/newsletters/etc.

Rank	Name	Usage	Average Impact
1	Hubspot	15,991	89 ms
2	OptinMonster	1,483	127 ms
3	Beeketing	62,659	149 ms
4	Drift	3,929	156 ms
5	Mailchimp	21,946	161 ms
6	Sumo	39,747	390 ms
7	Albacross	1,407	769 ms

Customer Success

These scripts are from customer support/marketing providers that offer chat and contact solutions. These scripts are generally heavier in weight.

Rank	Name	Usage	Average Impact
1	LiveChat	23,881	93 ms
2	Freshdesk	973	154 ms
3	Help Scout	665	198 ms
4	Olark	14,917	309 ms
5	Tawk.to	40,228	386 ms
6	ZenDesk	36,411	476 ms
7	Intercom	15,511	554 ms
8	Zopim	55,964	688 ms

Content & Publishing

These scripts are from content providers or publishing-specific affiliate tracking.

Rank	Name	Usage	Average Impact
1	AMP	60,944	196 ms
2	Vox Media	702	558 ms
3	Hotmart	1,008	814 ms

Libraries

These are mostly open source libraries (e.g. jQuery) served over different public CDNs. This category is unique in that the origin may have no responsibility for the performance of what's being served. Note that rank here does not imply one CDN is better than the other. It simply indicates that the libraries being served from that origin are lighter/heavier than the ones served by another..

Rank	Name	Usage	Average Impact
1	Bootstrap CDN	2,860	44 ms
2	FontAwesome CDN	17,002	102 ms
3	Yandex CDN	2,499	115 ms
4	jQuery CDN	170,001	154 ms
5	Cloudflare CDN	119,800	176 ms
6	Google CDN	811,231	178 ms
7	JSDelivr CDN	27,070	257 ms
8	CreateJS CDN	1,988	3188 ms

Mixed / Other

These are miscellaneous scripts delivered via a shared origin with no precise category or attribution. Help us out by identifying more origins!

Rank	Name	Usage	Average Impact
1	Amazon S3	35,291	152 ms
2	All Other 3rd Parties	1,649,095	198 ms
3	Google Tag Manager	1,093,167	386 ms
4	Parking Crew	4,021	428 ms

Third Parties by Total Impact

This section highlights the entities responsible for the most script execution across the web. This helps inform which improvements would have the largest total impact.

Name	Popularity	Total Impact	Average Impact
Google/Doubleclick Ads	1,412,404	466,442 s	330 ms
Google Tag Manager	1,093,167	421,590 s	386 ms
All Other 3rd Parties	1,649,095	326,279 s	198 ms
Wix	158,466	182,642 s	1153 ms
Facebook	1,212,567	145,169 s	120 ms
Google CDN	811,231	144,059 s	178 ms
Google Analytics	1,533,217	121,451 s	79 ms
Google APIs/SDK	977,712	112,781 s	115 ms
Yandex Metrica	217,229	81,926 s	377 ms
WordAds	30,961	78,744 s	2543 ms
AddThis	179,424	45,657 s	254 ms
Twitter	295,308	45,394 s	154 ms
Zopim	55,964	38,494 s	688 ms
Shopify	227,933	37,169 s	163 ms
Squarespace	86,605	35,683 s	412 ms
Hatena Blog	53,675	27,679 s	516 ms
jQuery CDN	170,001	26,146 s	154 ms
PIXNET	53,889	25,483 s	473 ms
33 Across	20,756	24,283 s	1170 ms
Yandex APIs	57,425	21,138 s	368 ms
Cloudflare CDN	119,800	21,084 s	176 ms
ZenDesk	36,411	17,340 s	476 ms
Tawk.to	40,228	15,541 s	386 ms
Sumo	39,747	15,492 s	390 ms
Tumblr	46,800	15,443 s	330 ms
WordPress	135,176	15,341 s	113 ms
Moat	23,170	14,281 s	616 ms
AMP	60,944	11,948 s	196 ms
Salesforce	40,451	11,786 s	291 ms
Yandex Ads	28,882	11,155 s	386 ms
Sentry	15,272	11,134 s	729 ms
OpenX	12,505	10,269 s	821 ms
Hotjar	108,933	9,724 s	89 ms
Beeketing	62,659	9,362 s	149 ms
Criteo	63,058	8,659 s	137 ms
ShareThis	39,884	8,618 s	216 ms
Intercom	15,511	8,588 s	554 ms
Popads	6,545	8,147 s	1245 ms
MediaVine	9,205	7,723 s	839 ms
Integral Ads	23,942	7,081 s	296 ms
JSDelivr CDN	27,070	6,959 s	257 ms
Adobe Analytics	34,436	6,617 s	192 ms
CreateJS CDN	1,988	6,337 s	3188 ms
Wistia	21,319	5,416 s	254 ms
Amazon S3	35,291	5,356 s	152 ms
Histats	15,770	5,343 s	339 ms
Lucky Orange	6,037	5,255 s	870 ms
Distil Networks	11,489	4,695 s	409 ms
Olark	14,917	4,610 s	309 ms
Taboola	23,818	4,357 s	183 ms
AppNexus	16,942	3,987 s	235 ms
Yandex Share	30,677	3,920 s	128 ms
OneSignal	41,178	3,641 s	88 ms
Mailchimp	21,946	3,544 s	161 ms
Optimizely	13,853	3,418 s	247 ms
Tealium	15,933	3,407 s	214 ms
Media Math	3,498	3,167 s	905 ms
MGID	10,472	2,902 s	277 ms
Brightcove	5,133	2,410 s	469 ms
YouTube	23,184	2,410 s	104 ms
LiveChat	23,881	2,216 s	93 ms
Yahoo Ads	8,495	2,098 s	247 ms
DoubleVerify	4,041	2,031 s	503 ms
FontAwesome CDN	17,002	1,728 s	102 ms
Parking Crew	4,021	1,720 s	428 ms
LinkedIn	10,663	1,659 s	156 ms
PayPal	6,376	1,539 s	241 ms
Segment	6,581	1,498 s	228 ms
Hubspot	15,991	1,430 s	89 ms
Sizmek	3,831	1,274 s	333 ms
Albacross	1,407	1,082 s	769 ms
Market GID	3,831	1,049 s	274 ms
Hotmart	1,008	821 s	814 ms
Pinterest	11,122	795 s	71 ms
Pubmatic	3,033	774 s	255 ms
Baidu Analytics	8,018	632 s	79 ms
Drift	3,929	615 s	156 ms
Cloudflare	3,151	584 s	185 ms
Mixpanel	7,258	573 s	79 ms
VK	7,578	460 s	61 ms
Scorecard Research	4,740	427 s	90 ms
Disqus	723	419 s	580 ms
Vox Media	702	392 s	558 ms
Yandex CDN	2,499	287 s	115 ms
App Dynamics	2,248	263 s	117 ms
Stripe	3,775	249 s	66 ms
Crazy Egg	2,214	201 s	91 ms
New Relic	3,613	189 s	52 ms
OptinMonster	1,483	188 s	127 ms
Freshdesk	973	150 s	154 ms
Help Scout	665	132 s	198 ms
Bootstrap CDN	2,860	126 s	44 ms
Alexa	1,721	96 s	56 ms

Future Work

1. Introduce URL-level data for more fine-grained analysis, i.e. which libraries from Cloudflare/Google CDNs are most expensive.
2. Expand the scope, i.e. include more third parties and have greater entity/category coverage.

FAQs

I don't see entity X in the list. What's up with that?

This can be for one of several reasons:

1. The entity does not have at least 100 references to their origin in the dataset.
2. The entity's origins have not yet been identified. See How can I contribute?

How is the "Average Impact" determined?

The HTTP Archive dataset includes Lighthouse reports for each URL on mobile. Lighthouse has an audit called "bootup-time" that summarizes the amount of time that each script spent on the main thread. The "Average Impact" for an entity is the total execution time of scripts whose domain matches one of the entity's domains divided by the total number of occurences of those scripts.

Average Impact = Total Execution Time / Total Occurences

How does Lighthouse determine the execution time of each script?

Lighthouse's bootup time audit attempts to attribute all toplevel main-thread tasks to a URL. A main thread task is attributed to the first script URL found in the stack. If you're interested in helping us improve this logic, see Contributing for details.

The data for entity X seems wrong. How can it be corrected?

Verify that the origins in data/entities.json are correct. Most issues will simply be the result of mislabelling of shared origins. If everything checks out, there is likely no further action and the data is valid. If you still believe there's errors, file an issue to discuss futher.

How can I contribute?

Only about 90% of the third party script execution has been assigned to an entity. We could use your help identifying the rest! See Contributing for details.

Contributing

Updating the Entities

The origin->entity mapping can be found in data/entities.json. Adding a new entity is as simple as adding a new array item with the following form.

{
    "name": "Facebook",
    "homepage": "https://www.facebook.com",
    "categories": ["social"],
    "origins": [
        "www.facebook.com",
        "connect.facebook.net",
        "staticxx.facebook.com",
        "static.xx.fbcdn.net",
        "m.facebook.com"
    ]
}

Updating Attribution Logic

The logic for attribution to individual script URLs can be found in the Lighthouse repo. File an issue over there to discuss further.

Updating the Data

The query used to compute the origin-level data is in sql/origin-execution-time-query.sql, running this against the latest Lighthouse HTTP Archive should give you a JSON export of the latest data that can be checked in at data/YYYY-MM-DD-origin-scripting.json.

Updating this README

This README is auto-generated from the template lib/template.md and the computed data. In order to update the charts, you'll need to make sure you have cairo installed locally in addition to yarn install.

# Install `cairo` and dependencies for node-canvas
brew install pkg-config cairo pango libpng jpeg giflib