A peer-to-peer note taking app: your devices sync with each other, not a cloud

What is a peer-to-peer note taking app?

It’s a notes app where your devices talk to each other instead of to a company’s server. There is no central copy of your notes in the cloud. Each device holds the whole workspace, works offline, and exchanges changes with your other devices when they can reach each other.

What does local-first mean?

Local-first software keeps the main copy of your data on your own device and treats the network as optional. The idea was set out by the research lab Ink & Switch in their 2019 essay “Local-first software”. Peer-to-peer sync is how a local-first app keeps several devices in step without a server holding your data.

• Read “Local-first software” →

How does Koru sync without a server?

Each workspace is a CRDT, a data structure built so that copies edited separately can be combined without a server deciding who wins. Koru uses Loro for the data and iroh to connect devices.

• On the same network, your devices connect to each other directly.
• On different networks, if they can’t reach each other directly, Koru’s relay forwards the traffic. The relay is run by Koru, not a third party, and stores nothing.
• You can turn the relay off on each device. Devices that can connect directly keep syncing; the rest waits for a direct path.
• With only one device, Koru exchanges nothing.

• Koru on GitHub →

How do I link my devices?

1. On your first computer, choose Link a device… from the profile switcher, the Welcome page or Manage › Linked devices.
2. The dialog shows a QR code and Copy link code. On the other computer, open Link a device… › Enter link code.
3. When it says Device linked, sync starts. Manage › Linked devices lists each device with its version, operating system and whether it’s connected directly or through a relay.

No account, email or password is needed to link your own devices. A Windows PC and a Mac link with each other the same way.

Is the sync encrypted?

Yes. Sync traffic between your devices is end-to-end encrypted, including when Koru’s relay forwards it, so the relay can’t read your notes.

• Private notes →

What are the limits?

Two devices exchange changes only when both are online at the same time. If your laptop is closed, your desktop gets its latest edits when it wakes up. Koru Cloud, an optional paid service coming soon, will keep an always-on copy for that case.

Pictures and files between two computers travel only over a direct connection, never through the relay, so between different networks they wait for Koru Cloud. Your notes themselves sync either way. Phone apps are in development and not released.

• Koru Cloud pricing →

How is Koru different from peer-to-peer notes projects on GitHub?

Projects like Paperus, SwarmNote and PeerFlow show the idea. Koru is a full desktop app with a rich editor, imports from Notion, Evernote, OneNote, Google Docs and Markdown, saved versions and a built-in terminal, with the same peer-to-peer sync underneath.

• Import options →