[jazzypants]

Just to clarify: I think an older version may have used React, but I just double-checked and current Reddit is definitely a Lit app built with web components. You can tell based on the comment placeholders used by the rendering engine as anchor nodes and by the prevalence of dashed-elements in the markup. Here's an example:

  <rpl-tooltip placement="top" appearance="neutral">
          <!--?lit$003985561$-->
          <span slot="content"><!--?lit$003985561$-->Send a GIF</span>
  </rpl-tooltip>

They seem to call the current architecture "shreddit" internally for some reason.

[Melatonic]

Probably "shhh" don't tell anyone how bad this version this is