Data study · Machine-readable doors for AI agents
1.6% of Top Websites Still Publish an OpenSearch Description, and 7.3% of the Top 1,000 Do
12,088 of 772,412 top homepages link to an OpenSearch description file, the format that lets browsers and software search a site directly. Much of it comes from wiki and community CMS software.
Analysis of 772,412 top-1M homepages · HTTP Archive, October 2026 crawl
Key findings
- 1
12,088 of 772,412 top-1M homepages (1.6%) link to an OpenSearch description with rel="search".
- 2
The top 1,000 sites are over four times as likely to have one: 54 of 738 (7.3%).
- 3
MediaWiki sites account for 2,977 files, and 99.7% of MediaWiki homepages have one.
- 4
75.2% of DataLife Engine and 22.9% of Joomla homepages publish one, against 0.5% of WordPress homepages.
- 5
Only 6 of 46,231 Shopify homepages (0.01%) link to an OpenSearch file.
Summary
A user types a few letters of a site's name into the browser bar and gets an offer to search that site directly. That shortcut comes from an OpenSearch description, a small XML file that explains how to run a search on the site.
OpenSearch dates back to 2005. It never became a headline SEO topic, but it is one of the few long-standing machine-readable ways to tell software how to query a site. As AI agents try to look things up on websites, a published search template is a simple door they could use.
We counted how many popular sites still publish one. 12,088 of the top 1 million homepages (1.6%) link to an OpenSearch file, and the most visited sites lead.
What we measured
We used the HTTP Archive October 2026 mobile crawl (httparchive.crawl.pages) for top-1M homepages and read link tags from the almanac link-nodes metric. A site counts when a link has rel containing search and a type containing opensearch, usually application/opensearchdescription+xml.
We did not fetch the XML files, so we cannot check that each one works. Platform comes from HTTP Archive's technology detection.
The biggest sites are the most likely to offer site search to software
Share by popularity rank.
% of homepages
| Rank bucket | Homepages | With OpenSearch link | % |
|---|---|---|---|
| Top 1K | 738 | 54 | 7.3 |
| 1K-5K | 2,920 | 133 | 4.6 |
| 5K-10K | 3,586 | 146 | 4.1 |
| 10K-50K | 28,831 | 781 | 2.7 |
| 50K-100K | 36,937 | 718 | 1.9 |
| 100K-500K | 306,048 | 4,702 | 1.5 |
| 500K-1M | 393,352 | 5,554 | 1.4 |
Source: aisearchoptimization.net analysis of 772,412 top-1M homepages · HTTP Archive, October 2026 crawl
Rates drop steadily with rank, from 7.3% at the top to 1.4% in the long tail. Large content sites with real search engines behind them are the natural users.
Wiki and community CMS software keeps OpenSearch alive
Platforms named for adoption only.
| Platform | Homepages | With OpenSearch link | % |
|---|---|---|---|
| MediaWiki | 2,985 | 2,977 | 99.7 |
| DataLife Engine | 1,659 | 1,247 | 75.2 |
| Joomla | 3,557 | 815 | 22.9 |
| TYPO3 CMS | 2,522 | 61 | 2.4 |
| Next.js | 36,899 | 216 | 0.6 |
| WordPress | 107,057 | 498 | 0.5 |
| Drupal | 11,424 | 58 | 0.5 |
| Shopify | 46,231 | 6 | 0 |
| Other or none detected | 496,664 | 6,050 | 1.2 |
Source: aisearchoptimization.net analysis of 772,412 top-1M homepages · HTTP Archive, October 2026 crawl
MediaWiki, DataLife Engine and Joomla together account for 5,039 of the 12,088 files (41.7%). Hosted store platforms and WordPress rarely include it.
Most sites with search do not describe it
How OpenSearch compares with other machine-readable entry points in the same crawl.
| Entry point | Homepages | % of homepages |
|---|---|---|
| llms.txt file | 110,188 | 14.3 |
| OpenSearch description link | 12,088 | 1.6 |
| Link to llms.txt in page head | 2,889 | 0.37 |
| Markdown alternate link | 951 | 0.12 |
Source: aisearchoptimization.net analysis of 772,412 top-1M homepages · HTTP Archive, October 2026 crawl
A 20-year-old format is still more common than newer AI-specific link tags, though far behind llms.txt.
What this means
If your site has a working search page, an OpenSearch file is a small addition: a short XML file and one link tag. It lets browsers, and any agent that reads the format, run searches on your site without guessing your search URL.
It will not change your rankings, so treat it as housekeeping after the basics. Once the basics are set, a free AI visibility audit shows whether assistants can find and quote you, and our generative engine optimization services take care of what is missing.
Limits
We counted link tags, not working files; some linked files may be broken.
Homepages only.
No growth trend: link tags sit in a large metric we chose not to rescan across past crawls.
We do not know which AI agents, if any, read OpenSearch files today.
Embed this research
Add the charts from this study to your page. The embed links back here.
<iframe src="https://aisearchoptimization.net/embed/data-studies/opensearch-description-adoption" title="OpenSearch Files: 1.6% of Top Sites Still Publish One" width="100%" height="720" style="border:0" loading="lazy"></iframe>
Cite this study
APA
Grenyo, K. (2026). OpenSearch Files: 1.6% of Top Sites Still Publish One. AI Search Optimization. https://aisearchoptimization.net/resources/data-studies/opensearch-description-adoption
Plain link
OpenSearch Files: 1.6% of Top Sites Still Publish One - AI Search Optimization - https://aisearchoptimization.net/resources/data-studies/opensearch-description-adoption
Frequently asked questions
What is OpenSearch?
A small XML format, linked with <link rel="search" type="application/opensearchdescription+xml">, that tells software how to run a search on your site.
How many websites use OpenSearch?
12,088 of 772,412 top-1M homepages (1.6%) in October 2026, including 7.3% of the top 1,000.
Which platforms include it by default?
The data points to MediaWiki (99.7% of homepages), DataLife Engine (75.2%) and Joomla (22.9%).
Does OpenSearch help AI search?
It gives software a documented way to query your site. Whether a given AI agent uses it is up to that agent, so it is a low-cost extra rather than a must.
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