devdocs.el is a documentation viewer similar to the built-in Info browser, but geared towards documentation obtained from the DevDocs website. It is available from GNU ELPA; to install, type M-x package-install RET devdocs RET.

To get started, download some documentation with M-x devdocs-install. This will first query https://devdocs.io for the available documents, and save to disk the selected document.

Once you have the desired documents at hand, call M-x devdocs-lookup to search for entries.

In any given buffer, the first call to devdocs-lookup will query for a list of documents to search (you can select more than one option by entering a comma-separated list). This selection will be remembered in subsequent calls to devdocs-lookup, unless a prefix argument is given; in this case you can select a new list of documents. Alternatively, you can set the devdocs-current-docs variable directly, say via dir-local variables or a mode hook:

(add-hook 'python-mode-hook
          (lambda () (setq-local devdocs-current-docs '("python~3.9"))))

In the *devdocs* buffer, navigation keys similar to Info and *Help* buffers are available; press C-h m for details. Internal hyperlinks are opened in the same viewing buffer, and external links are opened as browse-url normally would.