I started this project back in 2015, to translate the TeX original specification into an easily parsed format (s-doc), and to create an HTML rendering of that format as a proof of concept.

The project is homed here: https://codeberg.org/dlowe/metaspectre/

Differences from the Hyperspec (from the README):

  - Most importantly, it is free to modify and distribute.
  - The original TeX is very hard to parse and use for things other than
    generating a printed copy. The Hyperspec is an HTML rendering which
    can be parsed as HTML, but loses a lot of information. The Metaspec
    has an easily parsed intermediate form that can be used for all kinds
    of purposes, like converting into lookups.
  - Math equations are rendered using MathML.
  - Includes the acknowledgements and appendix sections.
  - Uses progressively enhanced Javascript to provide search and
    light/dark theme switching.
  - Incorporates over 145 patches for content, using corrections
    accumulated over the years, and documented in the errata page.
  - Includes TeX comments, which can contain interesting historical data.
  - Includes links and identifiers to bibliographical references.