Theorem

Free local-first reading app for EPUB, PDF, MOBI, CBZ and RSS

Desktopfree

Theorem is a free, open-source, local-first reading app for Linux, macOS, Windows and Android that reads EPUB, PDF, MOBI, FB2, CBZ and RSS feeds in one workspace. It supports highlighting, offline dictionary lookup, text-to-speech, and syncing highlights as Markdown files into an Obsidian or Logseq vault, with no cloud account required. It targets readers who want to keep their reading data and notes under their own control.

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Full match profile

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Problem & pain-point mapping
Who we surface it to (audience fit)
What it's a strong alternative to
Trust & credibility signals

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