The top .io websites by PageRank belong to developers and software companies. GitHub Pages, documentation hosts and open-source projects lead, followed by SaaS tools for analytics, forms and privacy notices.
The .io ending is the country code of the British Indian Ocean Territory, but tech startups adopted it because "IO" reads like input/output.
| # | Website | PageRank | Linking sites | Global rank | Compare |
|---|---|---|---|---|---|
| 1 | github.io | 9.41 | 170,009 | 50 | Compare |
| 2 | trustindex.io | 9.15 | 43,214 | 146 | Compare |
| 3 | plausible.io | 9.09 | 25,233 | 205 | Compare |
| 4 | sanity.io | 9.04 | 19,654 | 270 | Compare |
| 5 | readthedocs.io | 9.01 | 25,024 | 327 | Compare |
| 6 | complianz.io | 8.98 | 24,360 | 383 | Compare |
| 7 | webflow.io | 8.92 | 24,288 | 488 | Compare |
| 8 | statuspage.io | 8.89 | 7,486 | 538 | Compare |
| 9 | termly.io | 8.89 | 15,524 | 550 | Compare |
| 10 | codepen.io | 8.84 | 12,636 | 657 | Compare |
| 11 | borlabs.io | 8.81 | 13,801 | 728 | Compare |
| 12 | devowl.io | 8.77 | 9,870 | 830 | Compare |
| 13 | modelcontextprotocol.io | 8.75 | 9,932 | 895 | Compare |
| 14 | gitbook.io | 8.75 | 12,971 | 905 | Compare |
| 15 | itch.io | 8.75 | 14,237 | 910 | Compare |
| 16 | imagekit.io | 8.72 | 8,915 | 993 | Compare |
| 17 | kubernetes.io | 8.72 | 10,118 | 997 | Compare |
| 18 | greenhouse.io | 8.71 | 9,485 | 1,040 | Compare |
| 19 | sentry.io | 8.70 | 7,653 | 1,073 | Compare |
| 20 | gohugo.io | 8.69 | 8,886 | 1,112 | Compare |
| 21 | polyfill.io | 8.68 | 7,127 | 1,150 | Compare |
| 22 | formspree.io | 8.67 | 6,165 | 1,186 | Compare |
| 23 | shields.io | 8.67 | 7,463 | 1,189 | Compare |
| 24 | prismic.io | 8.67 | 8,534 | 1,193 | Compare |
| 25 | pantheonsite.io | 8.64 | 9,704 | 1,345 | Compare |
Data: Open PageRank, data file October 2026. Domain data derived from Common Crawl. Not Google's own PageRank.
Why the top .io websites are widgets and hosts
Some .io services sit inside other websites: a review widget, a cookie banner or a status page. Every site that embeds one links back to it, so the score climbs fast even when few people visit the service itself.
Hosting domains like GitHub Pages also collect links for every project they host. That is why they rank above many famous apps.
Browse the top .io websites to find tools your own site may already use, and compare them in the checker.
Frequently asked questions
What does .io stand for?
It is the country code of the British Indian Ocean Territory. Tech companies like it because IO also means input/output.
Why is github.io at the top?
GitHub Pages hosts millions of project sites on github.io, and the links to all of them count for the whole domain.
Is a .io domain good for SEO?
Google treats .io like a generic ending, not a country site. The ending itself does not raise your score; links do.