Next Up: Limestone

Written by Finn Williams

•

April 21, 2025
announcement

What is Limestone?

Limestone is an open-source, free-to-use note-taking application currently in development by Voithos Labs. Local-first (no account required), extendable, and built to organize anything from a few notes to hundreds of thousands.

Why?

Straight to the meat. We're working on this because no existing application satisfies our note-taking needs sufficiently.

Here's what's good and bad about the popular options today:

Obsidian

Good:

  • Local-first, free to use. Everything is .md files on your device. You own your data, no vendor lock-in.
  • Extendable. Massive community plugin ecosystem -- spaced repetition, custom canvases, whatever you want.

Bad:

  • Paid cloud sync.
  • Closed source. A vibrant plugin community propping up a closed core. Plugin devs contribute for free, control and monetization stay with the vendor. This is upsetting to me.
  • Lackluster editor. The editing experience is Markdown-first, and "Live Preview" does not work for me, not a rich text editor. Not everyone likes Markdown. Not everyone who likes Markdown likes it all the time.
  • Plugin dependency. Out of the box it's sparse. You end up stitching together plugins until it resembles a usable tool, then maintaining that stitching forever.
  • No version history without plugins or a paid plan. Basic undo/redo only.
  • No peer collaboration.

Notion

Good:

  • Polished editing experience. Clean, modern UI, if a little busy.
  • Highly customizable workflows. Notion seems cool when you're building a very specific system -- databases, dashboards, project templates.
  • Collaboration ready. Real-time multiplayer editing, inline comments, permissions. Decent for small teams.

Bad:

  • Freemium pressure. Version history, guest limits, and attachment size limits all funnel you toward paid tiers.
  • The customization paradox. Notion is customizable but not usable out of the box. You spend hours building the thing before the thing is useful. Some people enjoy this. They are building dashboards, not taking notes.
  • Cloud-only and proprietary. You don't own your data. Exports are lossy. Full vendor lock-in.
  • Bloated. OKRs, CRMs, full-scale project management -- features for someone, presumably, but most of us just want decent notes.

OneNote

Good:

  • Drawing and handwriting support. Genuinely great on a tablet or with a drawing pad.

Bad:

  • Unstructured. Freeform canvas is good for sketches, bad for anything you intend to find again.
  • Buggy and bloated. Sync issues, inconsistent UI, crashes.
  • Weak search and navigation. Especially painful once notebooks get large, which is exactly when you need them.
  • Microsoft lock-in. Tight Office integration. This is never a good thing.

So what makes a note-taking app good?

"Okay Finn, you've complained lots, what do you actually want, you babbling buffoon?"

Uhh, something like:

  • Free, local-first, and open-source
  • Simple, modern UI with real customization
  • Extendable and scriptable
  • Collaboration, sync, and version history
  • Runs everywhere, including web

None of these are exotic. The fact that no single app manages all five is the entire reason this project exists.

The Big List

A sample of what's coming to Limestone:

  • Blocks: rich, highly-extendable, structured blocks with Markdown/LaTeX compatibility and visual elements: todo lists, graphs, drawings, calendars, code. Interchangeable with LaTeX and Markdown, PDF export, backed by reusable web components. We'll cover the Blocks system properly in an upcoming post.
  • Note organization: a flexible system based on groups, combining traditional folder hierarchies with tag-based classification. Plus organic organization -- configurable semantic analysis that groups related content naturally over time.
  • Executable code blocks: run code directly inside notes using local runtimes. Think Jupyter, but more flexible and ultra simple to use. C/C++, Rust, Java, R [+vis], Python [+vis], Julia [+vis], JS/TS [+vis], C#, Go -- where [+vis] means built-in graph/plot output. Any locally-runnable language can be added.
  • Peer collaboration: both live and dead-simplebranching for offline collaborative editing.
  • Material ingestoin: import PDFs, text files, Google Docs, and more, with immediate search support.
  • Import support: bring in existing note collections, Markdown exports, LaTeX projects, or random directories you swear you'll organize someday.
  • Appearance customization: colors, themes, fonts, symbols -- change everything.
  • Internal linking: notes link organically as you write.
  • And more. Follow the blog.

And of course:

  • Good multilingual text-to-speech, with cloud and local model support.
  • Good speech-to-text, using local Whisper with lean LLM postprocessing for accuracy. Local or cloud, so older devices aren't left out.
  • Good search, extremely fast even across hundreds of thousands of notes. Title search, content search, and semantic search.

Limestone Data Structure (for nerds)

Groups
|-- Flexible organization system
|-- Combines:
|   |-- Folder-based hierarchy (can mirror filesystem)
|   `-- Tag-based classification (overlapping, supersets hierarchy)
|-- Supports automatic semantic grouping (configurable)
`-- Represents a group of documents
    `-- Documents
        |-- Markdown files
        |-- LaTeX documents
        |-- PDFs
        |-- Plaintext files (e.g., code, CSVs)
        |-- External documents (e.g., Google Docs)
        `-- Block documents
            `-- Blocks
                |-- Atomic, modular content units
                |-- Rendered by standalone web components
                |-- Highly extensible
                `-- Exportable to Markdown, PDF, LaTeX

Thanks for reading!

Limestone is in active development -- if this sounds like something you'd use (or help build), we'd love to hear from you. More posts soon.

Contact: contact@voithoslabs.com

Blog: voithoslabs.com/blog