https://github.com/avelino/outl
Local-first outliner. Markdown is the source of truth. Sync that doesn't corrupt your tree when two devices edit offline
https://github.com/avelino/outl
markdown notes-app outliner
Last synced: 27 days ago
JSON representation
Local-first outliner. Markdown is the source of truth. Sync that doesn't corrupt your tree when two devices edit offline
- Host: GitHub
- URL: https://github.com/avelino/outl
- Owner: avelino
- License: mit
- Created: 2026-05-24T14:04:46.000Z (about 1 month ago)
- Default Branch: main
- Last Pushed: 2026-05-30T10:17:47.000Z (28 days ago)
- Last Synced: 2026-05-30T12:20:17.477Z (28 days ago)
- Topics: markdown, notes-app, outliner
- Language: Rust
- Homepage:
- Size: 12.4 MB
- Stars: 3
- Watchers: 0
- Forks: 0
- Open Issues: 18
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- Contributing: CONTRIBUTING.md
- License: LICENSE
- Security: SECURITY.md
- Roadmap: docs/roadmap.md
Awesome Lists containing this project
README
outl
Local-first outliner. Markdown is the source of truth. Sync that
doesn't corrupt your tree when two devices edit offline.
Inspired by [Roam Research](https://roamresearch.com) and
[Logseq](https://logseq.com). Picks what they got right (graph,
backlinks, daily journal, block-level thinking) and fixes the part
they didn't.
## The bet — a sync that's *provably* correct
This is the differentiator. Everything else builds on it.
Roam keeps your notes on their servers; if two devices edit while
offline, the later write silently wins. Logseq scatters `id::` UUIDs
through your `.md` so its rsync-flavoured "sync" has something to
match on; concurrent moves still lose data. `git`-as-sync produces
conflict markers across nested bullets every time.
outl uses the **[Kleppmann et al. 2022 tree CRDT][paper]** — the
same family of algorithm that backs Automerge and Y.js, adapted
specifically for trees. Two devices that edit a workspace offline
and then sync produce **exactly the same tree**, with **no data
loss**, **without a server**, and **without polluting your
`.md`**. The IDs CRDTs need to operate live in a separate sidecar
file (`foo.outl` next to `foo.md`), so the markdown you see is the
markdown you wrote — no `id::` lines, no UUIDs, no HTML comments.
Five formal guarantees, each backed by a test in
[`crates/outl-core/tests/`](crates/outl-core/tests/):
1. **Strong eventual consistency** — same set of ops → same tree, any order.
2. **Commutative after reordering** — late arrivals don't break the result.
3. **Idempotent** — applying an op twice is the same as once.
4. **Tree invariant always holds** — no node ever has two parents, no cycles.
5. **No silent loss** — every op stays in the log, even ones turned into no-ops by cycle detection.
→ **[Sync, done right](docs/sync.md)** walks through *why* Roam,
Logseq and Git fail, then the algorithm step by step.
→ **[Tree CRDT walkthrough](docs/crdt.md)** is the algorithm with code.
**Working sync today.** outl already syncs across a macOS TUI and an
iOS mobile app via iCloud Drive: one `ops-.jsonl` per device,
no central server, no merge dialogs. The Kleppmann move-op core sits
under everything; iCloud is just transport. P2P (iroh) on
[the roadmap](docs/roadmap.md) replaces the transport later without
touching the algorithm.
[paper]: https://martin.kleppmann.com/papers/move-op.pdf
## What's in the box today (0.1.0)
- **TUI** — journal-first, vim-style keys, slash commands (`/`),
fuzzy switcher (`Ctrl+P`), workspace search, multi-line blocks,
fenced code blocks, themes, hot-reload on external `.md` edits.
- **Markdown clean as you wrote it** — `title::`, `icon::`, `tags::`
properties live in plain `key:: value` lines at the top; outline
is standard CommonMark bullets. No metadata smuggled in.
- **Page icons** — `icon:: 🚀` on a page surfaces everywhere it's
referenced (header, switcher, backlinks panel, `[[ref]]` inline).
- **Block references and embeds** — `((blk-XXXXXX))` resolves inline
to the source block's text + page icon. `!((blk-XXXXXX))` expands
the source block **and its children** read-only below the carrying
block (each row prefixed with `↳ `, children indented to align with
the source's text). `Enter` on any handle jumps to the source page
and lands the cursor on the referenced block. Short, deterministic,
sidecar-backed handles — the `.md` stays human-typeable. `((` in
Insert mode pops a fuzzy-match autocomplete; `y r` (or `/refer` /
`/refer-embed`) copies the current block's handle to the OS
clipboard for paste anywhere.
- **Code blocks that run** — ` ```lisp / ```js / ```python / ```lua /
```rust `, the result lands as a `> **result:**` subblock under
the source. Re-runs are idempotent. Set `auto-run::` on a block
and it re-runs whenever you open the page (cache-aware by source
hash). Powered by [`outl-exec`](crates/outl-exec/) — language
registry is plugin-shaped, more languages drop in as 80-line
adapters.
- **Importers** — `outl import logseq` and `outl import roam`
strip `id::` lines, resolve `((uid))` block refs, slugify
filenames, seed sidecars.
- **Bench harness** — `cargo bench -p outl-md` measures parse +
index over synthetic workspaces from 15 files up to 10.500. CI
runs the smaller tiers on every PR; the 10k-file tier on a
weekly cron.
## Quick start
```bash
git clone https://github.com/avelino/outl.git && cd outl
cargo build --release
./target/release/outl init ~/notes
./target/release/outl --path ~/notes
```
`outl` (no subcommand) opens the TUI on the workspace and lands on
today's journal. Press `?` for keymap, `:` for the command palette,
`Ctrl+P` to fuzzy-jump to any page.
## Coming from Logseq or Roam?
```bash
outl import logseq ~/path/to/logseq-graph ~/notes
outl import roam ~/Downloads/backup.json ~/notes
```
The importer strips `id::` lines, resolves `((uid))` block refs to
page links, slugifies filenames, and seeds the sidecars. Anything it
can't resolve stays as `((unresolved:UID))` for manual triage.
## Status
**0.3.0 — cross-device daily driver.** Workspace, TUI, and iOS mobile
app share the same `outl-core` + `outl-md` + `outl-actions` stack and
sync across devices via iCloud Drive. The CRDT, op log, sidecar, and
reconcile pipeline are working end-to-end (edit on the laptop, the
iPhone updates within seconds; concurrent edits converge without
prompts). The P2P transport (iroh, phase 2) and the Tauri desktop
shell (phase 5) are still ahead — see [the roadmap](docs/roadmap.md).
The mobile client is Tauri 2 + SolidJS, which replaces the earlier
uniffi plan (decision in [`docs/architecture.md`](docs/architecture.md)).
## Docs
Want to actually learn how this works?
→ **[docs.outl.app](docs/README.md)** — full GitBook, with the sync
algorithm walked through step by step, the TUI manual, theming, and
contributing notes.
## Background reading
The engineering decisions behind outl are written up on
[avelino.run](https://avelino.run) as the project moves:
- **[File sync isn't trivial](https://avelino.run/file-sync-isnt-trivial/)**
— why concurrent file moves are a distributed-systems problem that
Dropbox and Google Drive still get wrong, and what the Kleppmann
et al. 2022 paper proves about a path out.
- **[From paper to outliner](https://avelino.run/from-paper-to-outliner/)**
— the gap between "the CRDT converges" and "the app ships":
projections, content-addressable reconciliation, ignoring your own
writes, surviving iCloud's lazy materialisation.
## License
[MIT](LICENSE).