A local-first notes and GTD app for people who take thinking seriously.

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I built Cairn to cover a gap I had with my Obsidian setup that I just couldn't achieve with plugins no matter how hard I tried. I wanted a neat way to capture my thoughts on the fly while working, go through > and expand on them in a simple way, and finally organize my knowledge across all projects in an LLM-friendly way. Earlier this year, I picked up a copy of David Allen's Getting Things Done and took a few principles and put a twist on them in a way that works for me. This new structure dramatically increased my productivity towards the latter half of 2025, and Cairn implements that system natively. I already use it daily, and if it helps one person get a step closer to their goals then it'll have fulfilled its purpose.

Watch it in action

The quick-capture flow. A global shortcut, a floating dialog, a note on disk.

What Cairn is

Cairn is a desktop application for capturing, organizing, and acting on your thoughts. It borrows Obsidian's markdown-first discipline and David Allen's Getting Things Done methodology, and applies them to a single promise: your knowledge stays yours.

Every note is a plain .md file in a folder you chose. A small .cairn/ directory inside each vault holds config, state, the reminder index, and soft-deleted notes. Everything else is your markdown, readable by any editor, backup-friendly, and future-proof.

There is no cloud, no sync, no telemetry, no account.

A quick tour

Home

Your day at a glance. Open actions across every project, sorted however you dragged them. Reminders firing today. Recent activity so you can pick up where you left off.

Captures

The inbox. Quick thoughts, meeting notes, half-baked ideas. Process later, move into a project when the shape is clear, or send to Someday if it's not ready.

Projects

A project is a folder. Loose notes live at the root, GTD action items live under Actions/, and you can nest subfolders as deep as you want. The breadcrumb follows you.

The editor

CodeMirror 6 with a full live-preview pipeline. Full GitHub Flavored Markdown: tables render as real HTML, task-list checkboxes click, images load inline, ~~strikethrough~~ does what it says. Syntax markers hide when the cursor isn't on them, so the markdown source stays clean.

Features at a glance

• Captures. A drop-anything inbox for quick thoughts, memos, and pastes.
• Projects and Actions. Project folders for knowledge, Actions/ folders for GTD work. Completed actions archive alongside the file with an optional reflection note.
• Someday. Parked ideas with preset reminders (tomorrow, in a week, in a month) that fire via OS notifications and in-app toasts.
• Live-preview editor. Headings, bold, italic, inline code, strikethrough, links, images, task lists, and GFM tables all render as you type. The markdown source stays untouched.
• Image paste. Drop an image into a note, Cairn writes it to the nearest assets/ dir and inserts a relative link.
• Tags. Apply via frontmatter or the metadata bar. Rename or recolor across the whole vault in one action. Unknown frontmatter keys are preserved verbatim.
• Command palette. Ctrl/Cmd + K for navigation and full-text search across the vault.
• Quick Capture. A system-wide keyboard shortcut opens a small floating window for capturing without leaving whatever you were doing.
• Trash with restore. Soft-delete into .cairn/trash/ with a mirrored path. One click to restore, with collision-rename if needed. Empty Trash permanently removes.
• Multi-vault. Register several vaults and switch from the sidebar.
• File-watcher-aware. Edits made by external tools (another editor, git pull) surface in the UI within a debounce window.

Design principles

• Local-first. Nothing leaves your machine.
• Plain markdown. Your files are readable by any editor. Cairn is a lens on them, not a container.
• Unknown frontmatter is sacred. Hand-written YAML keys survive every round-trip. Cairn only touches fields it understands.
• Calm focus. Dark-first, restrained visual language inspired by Linear and Arc. One accent color (#fac775), used sparingly.

Tech stack

• Backend: Rust, Tauri 2
• Frontend: React 18, TypeScript, Vite, Tailwind CSS, CodeMirror 6, cmdk, dnd-kit
• Storage: plain .md files plus a small .cairn/ config directory per vault

Deeper references: docs/ARCHITECTURE.md for the module map and IPC contract, docs/EDITOR.md for the live-preview editor, docs/DESIGN.md for tokens and component rules, CLAUDE.md for coding conventions.

Prerequisites

• Rust 1.77 or newer (install)
• Node.js 20 or newer
• pnpm 10 or newer (npm install -g pnpm)
• Windows: WebView2 runtime (bundled with Windows 11)
• macOS: Xcode Command Line Tools (xcode-select --install)
• Linux: webkit2gtk-4.1, libssl-dev, libgtk-3-dev, libayatana-appindicator3-dev, librsvg2-dev

Install

git clone https://github.com/amerkld/cairn.git
cd cairn
pnpm install

The first build compiles the full Tauri and Rust toolchain and takes a few minutes. Subsequent builds are fast.

Run

# Hot-reload dev: Vite for the frontend, cargo watch for the Rust side.
pnpm tauri:dev

On first launch, Cairn prompts you to pick a folder to use as your vault. Any folder works. Cairn writes a .cairn/ subdirectory into it and leaves the rest for you.

# Production build. Produces installers (NSIS + MSI on Windows) under
# src-tauri/target/release/bundle.
pnpm tauri:build

A ready-made dev / demo vault lives at sample/ if you want something to point Cairn at right after installing.

Development

Frontend:

pnpm typecheck
pnpm test
pnpm lint
pnpm build

Backend:

cd src-tauri
cargo test
cargo clippy

See CLAUDE.md for the testing discipline and code-quality rules.

Keyboard shortcuts

Keys	Action
Ctrl/Cmd + K	Open the command palette
Ctrl/Cmd + N	New capture
Ctrl/Cmd + Shift + N	Open Quick Capture (global, even when Cairn isn't focused)
?	Show the keyboard shortcuts sheet

Roadmap

The daily-driver scope is shipping. What's next, roughly ordered:

• File sync. Optional, end-to-end-encrypted sync so a vault can live on more than one machine without giving up local-first. The source of truth stays on disk. Sync is additive, never required.
• Local and BYOK LLM integration. A writing and thinking assistant that can read your vault with your permission. Runs either against a local model (Ollama, LM Studio, llama.cpp) or a provider you've supplied a key for (Anthropic, OpenAI, Google). No data leaves the machine unless you deliberately choose a cloud model.
• Plugins. A typed extension API for third-party views, commands, and editor decorations. The core stays small. The ecosystem can stretch.
• Mobile^*. A read-and-capture companion app for iOS and Android, sharing a vault with the desktop over the sync layer above.

_{^* Long term. Revisit once the sync and plugin foundations are stable.}