Detect H2O
H2O is a fast and secure HTTP/2 server written in C by Kazuho Oku.
Detection looks at response headers, cookies across 2 fingerprint rules among the site's public responses.
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Websites using H2O
Loading website list…
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Signal classes
PluginView evaluates public page signals in these classes when identifying H2O. Individual fingerprint rule bodies are proprietary and are not published.
- Response headers
- Cookies
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Example public indicators for H2O
Illustrative indicators derived from public catalog metadata for H2O. A live scan may match additional proprietary rules beyond these examples.
- server: h2o/??
- h2o_casper
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What a detection means
- Establishes
- One or more public signals on the scanned page matched a known H2O signature (2 rules) at the time of the scan.
- Does not establish
- A sitewide install of H2O, an active vendor contract, exclusive use, or that H2O is still in place today.
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How to check a site for H2O
- 1. Enter the website URL in the scan form — homepage, pricing, checkout, or login pages usually expose the strongest H2O signals.
- 2. PluginView reads only public responses (response headers, cookies) and scores them against the H2O signature set (2 rules).
- 3. Review the confidence score and text explanation for H2O on the results page.
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Commonly implies
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FAQ: detecting H2O
- Can PluginView detect H2O without logging in?
- Yes. PluginView only reads publicly accessible responses when checking for H2O — typically response headers, cookies. It does not bypass authentication or paywalls.
- What category is H2O?
- H2O is classified under Web servers in the PluginView directory.
- How many fingerprint rules cover H2O?
- This reference currently tracks 2 fingerprint rules across response headers, cookies. Individual rule bodies are proprietary and are not published.
- What public signals suggest a site uses H2O?
- Illustrative public indicators for H2O include server: h2o/??; h2o_casper. A live scan may match additional proprietary rules beyond these examples.
