--- title: "Sphinx: vendor profile: Agent Ready HTML" description: "Sphinx, a framework: 1 of 6 standards stated as supported, 14 sourced facts, dated plans and what it does not do. Read 2026-11-05." canonical: https://agentreadyhtml.com/vendors/sphinx/ site: "Agent Ready HTML" last_updated: 2026-11-05 section: "Vendors" --- # Sphinx: vendor profile: Agent Ready HTML > Sphinx, a framework: 1 of 6 standards stated as supported, 14 sourced facts, dated plans and what it does not do. Read 2026-11-05. Source: https://agentreadyhtml.com/vendors/sphinx/ Site: Agent Ready HTML Last reviewed: 2026-11-05 # Sphinx: vendor profile In short Sphinx writes a static HTML file per page and keeps page sources under \_sources/, but its core has no Markdown builder, and a 404.html, sitemap.xml or llms.txt each need an extension. Sphinx's own site answers Accept: text/markdown through its host, Read the Docs. Sphinx 9.2.0 came out on 2026-10-20 under a BSD licence. ## At a glance **standards.txt** sphinx ```text llms-txt = partial markdown-negotiation = no statement markdown-twin = partial initial-html = supports real-404 = partial vary-accept = no statement ``` 1 supports, 3 partial or announced, 2 no statement. **Sphinx** Framework Python documentation generator whose html builders write a static HTML file per page and copy page sources into \_sources/; llms.txt, 404 pages and sitemaps come from third-party extensions. Type [Framework](https://agentreadyhtml.com/vendors/by-type/framework/) Operator, as the facts below state it Sphinx team (sphinx-doc) Home page [www.sphinx-doc.org](https://www.sphinx-doc.org/), answered HTTP 200 on 2026-11-05 Last read 5 November 2026 ## What it does for this layer - Sphinx's standard html builder writes a directory of HTML files with style sheets and, optionally, the reStructuredText sources. \[primary source\] [source](https://www.sphinx-doc.org/en/master/usage/builders/index.html), read 5 November 2026. - Sphinx's dirhtml builder writes each page as /index.html, so links read like markup/rest/ without the file name. \[primary source\] [source](https://www.sphinx-doc.org/en/master/usage/builders/index.html), read 5 November 2026. - Sphinx's built-in text builder writes one plain text file per reStructuredText file with much of the markup stripped; Sphinx core lists no Markdown builder. \[primary source\] [source](https://www.sphinx-doc.org/en/master/usage/builders/index.html), read 5 November 2026. - html\_copy\_source defaults to True, so Sphinx copies each page's source into \_sources/ with a .txt suffix, a plain source twin rather than rendered Markdown. \[primary source\] [source](https://www.sphinx-doc.org/en/master/usage/configuration.html), read 5 November 2026. - Sphinx's html\_baseurl, empty by default and added in 1.8, sets the documentation root used for the canonical link relation. \[primary source\] [source](https://www.sphinx-doc.org/en/master/usage/configuration.html), read 5 November 2026. - Sphinx 9.2.0, released on 2026-10-20, dropped Python 3.12 and added support for Docutils 0.23. \[primary source, 2026-10-20\] [source](https://www.sphinx-doc.org/en/master/changes/index.html), read 5 November 2026. - Sphinx lists HTML, LaTeX for PDF, ePub and Texinfo among its output formats, with authoring in reStructuredText or MyST Markdown. \[primary source\] [source](https://www.sphinx-doc.org/en/master/), read 5 November 2026. - The community extension sphinx-llms-txt writes llms.txt in Markdown and a combined llms-full.txt in reStructuredText during a normal Sphinx build once added to conf.py. \[secondary source\] [source](https://sphinx-llms-txt.readthedocs.io/en/latest/), read 5 November 2026. - The sphinx-llms-txt docs point readers to sphinx-llm from NVIDIA for stronger default output without configuration. \[secondary source\] [source](https://sphinx-llms-txt.readthedocs.io/en/latest/), read 5 November 2026. - Sphinx makes no 404 page of its own; Read the Docs' sphinx-notfound-page extension builds one whose CSS, JS and image links still resolve on deep URLs. \[secondary source\] [source](https://sphinx-notfound-page.readthedocs.io/en/latest/), read 5 November 2026. - Sitemaps for Sphinx come from the third-party sphinx-sitemap extension, which writes sitemaps.org files across versions and languages. \[secondary source\] [source](https://sphinx-sitemap.readthedocs.io/en/latest/), read 5 November 2026. - www.sphinx-doc.org, built by Sphinx and hosted on Read the Docs, answered Accept: text/markdown on the quickstart page with text/markdown and Vary: Accept-Encoding, accept on 2026-11-05; x-rtd headers show Read the Docs produced that variant. \[observed\] [source](https://www.sphinx-doc.org/en/master/usage/builders/index.html), read 5 November 2026. - The quickstart source copy at /en/master/\_sources/usage/quickstart.rst.txt on www.sphinx-doc.org answered 200 text/plain on 2026-11-05, while /llms.txt on the same host was a 404. \[observed\] [source](https://www.sphinx-doc.org/en/master/usage/configuration.html), read 5 November 2026. - Sphinx code is licensed under the two-clause BSD licence, copyright 2007-2026 the Sphinx team. \[primary source\] [source](https://raw.githubusercontent.com/sphinx-doc/sphinx/master/LICENSE.rst), read 5 November 2026. ## Products and plans | Product | What it is | Price | As of | Source | | --- | --- | --- | --- | --- | | Sphinx | Python documentation generator with HTML, LaTeX, ePub and text builders. | Free, open source; BSD 2-clause licence, free; 9.2.0 on 2026-10-20 | 2026-11-05 | source | ## Standards | Standard | Status | What the vendor's pages say | Source | | --- | --- | --- | --- | | llms-txt | partial | Only through the third-party sphinx-llms-txt extension (or NVIDIA's sphinx-llm); Sphinx itself writes no llms.txt. | source | | markdown-negotiation | no statement | No statement found in the Sphinx builders or configuration pages; the Markdown answer seen on www.sphinx-doc.org comes from Read the Docs hosting. | none | | markdown-twin | partial | html_copy_source puts each page's source under _sources/ as .txt, which is Markdown only when the project is written in MyST. | source | | initial-html | supports | The standard html builder outputs a directory of HTML files. | source | | real-404 | partial | Sphinx creates no 404 page by default; the sphinx-notfound-page extension adds one, and the status code depends on the host. | source | | vary-accept | no statement | No statement found in the Sphinx builders, configuration or changelog pages; Sphinx outputs files and sets no headers. | none | ## Checks on its own site | Reading | Result | Date | | --- | --- | --- | | Home page request | HTTP 200; H1 in the initial HTML: yes; 777 words; 0 JSON-LD blocks | 2026-11-05 | | Request with Accept: text/markdown | HTTP 200, text/markdown, Vary: Accept-Encoding, accept | 2026-11-05 | | /llms.txt at the host root | HTTP 404, text/html, 2.3 KB | 2026-11-05 | | A made-up path | HTTP 404 | 2026-11-05 | | Ora score, cached | Not available: GET /api/score returned 404 DOMAIN_NOT_SCANNED | 2026-11-05 | | Cloudflare keyless scan | 27, L1 Basic Web Presence | 2026-11-05 | | Shared crawl row | Tranco rank 8,556; home page HTTP 200; H1 in the HTML: yes; 780 words; JSON-LD types: none; answers markdown: yes; made-up path HTTP 404; llms.txt valid: no | 2026-11-04 | ## What it does not do - Sphinx does not write a 404.html, a sitemap.xml or an llms.txt without extensions such as sphinx-notfound-page, sphinx-sitemap and sphinx-llms-txt. ## Related pages on this site - [Frameworks in this section](https://agentreadyhtml.com/vendors/by-type/framework/) - [The Plain Fetch viewer](https://agentreadyhtml.com/viewer/) ## Sources 1. [Sphinx: home page](https://www.sphinx-doc.org/) https://www.sphinx-doc.org/, read 5 November 2026 2. [Builders: Sphinx documentation](https://www.sphinx-doc.org/en/master/usage/builders/index.html) https://www.sphinx-doc.org/en/master/usage/builders/index.html, read 5 November 2026 3. [Configuration: Sphinx documentation](https://www.sphinx-doc.org/en/master/usage/configuration.html) https://www.sphinx-doc.org/en/master/usage/configuration.html, read 5 November 2026 4. [Changelog: Sphinx documentation](https://www.sphinx-doc.org/en/master/changes/index.html) https://www.sphinx-doc.org/en/master/changes/index.html, read 5 November 2026 5. [Sphinx: Sphinx documentation](https://www.sphinx-doc.org/en/master/) https://www.sphinx-doc.org/en/master/, read 5 November 2026 6. [sphinx-llms-txt documentation](https://sphinx-llms-txt.readthedocs.io/en/latest/) https://sphinx-llms-txt.readthedocs.io/en/latest/, read 5 November 2026 7. [sphinx-notfound-page documentation](https://sphinx-notfound-page.readthedocs.io/en/latest/) https://sphinx-notfound-page.readthedocs.io/en/latest/, read 5 November 2026 8. [sphinx-sitemap documentation](https://sphinx-sitemap.readthedocs.io/en/latest/) https://sphinx-sitemap.readthedocs.io/en/latest/, read 5 November 2026 9. [License for Sphinx (LICENSE.rst)](https://raw.githubusercontent.com/sphinx-doc/sphinx/master/LICENSE.rst) https://raw.githubusercontent.com/sphinx-doc/sphinx/master/LICENSE.rst, read 5 November 2026 Last reviewed 5 November 2026 Edition Crawl 2026-11-04 Page updated 2026-11-05 Method How the viewer reads a page, how a file is graded and how a platform is scored: [the method page](https://agentreadyhtml.com/method/).